articles+ search results

CATALYSTS, DESULFURIZATION, CARBON emissions, ORGANIC chemistry, CARBON disulfide, and INTERMEDIATES (Chemistry)

Hydrodesulfurization is well established in the industry while costly and environmentally unfriendly due to CO 2 emissions and H 2 S production. An alternative, cost-effective desulfurization process remains unreported. Here, we demonstrate a desulfurization process for dibenzothiophene, one of the most well-known and recalcitrant sulfur-containing model compounds against catalytic desulfurization, under the regulation of methane instead of hydrogen over a combination of two catalysts, generating a new sulfur-containing product, CS 2 , as an important intermediate in organic chemistry and non-polar solvent with lower environmental impact than H 2 S. A catalytic mechanism is proposed and supported by extensive experimental and computational evidence. It is discovered that methane acts as a critical initiator and intensifies the direct desulfurization pathway, where two catalysts must work cooperatively and a surface sulfur transfer process is indispensable. This study explores an alternative desulfurization route with unique reaction pathways towards CS 2 formation, whose practical potential is also supported by the desulfurization performance over a series of real-world crude samples. [Display omitted] • Methane-regulated catalytic desulfurization of dibenzothiophene is realized. • Methane initiates a direct desulfurization pathway and ends up in final products. • Carbon disulfide is observed as an environmentally benign sulfur-containing product. • A dual catalyst system is designed and the mechanism is proposed and verified. • Real-world sample desulfurization practices confirm the technical feasibility. [ABSTRACT FROM AUTHOR]

DIAMINES, MOLECULAR docking, CYTOCHROME c, SCHIFF bases, PEROXIDASE, ESCHERICHIA coli, and DENSITY functional theory

• Synthesis of symmetrical bis-benzoxazines. • Density Functional Theory (DFT) estimation was disclosed for compound 5e. • A Molecular docking study was carried out against Cytochrome c Peroxidase (2 × 08). • Compounds 3 g, 4 g, 5c, and 5 g showed remarkable antimicrobial activity. • Compounds 3b, 3c, 3 g, 4c, 5b, & 5f displayed good antioxidant activity. We herein report the efficient synthesis of symmetrical bis-benzoxazines by substituted salicylaldehydes and alkyl diamines. The substituted salicylaldehydes (1a-d) and alkyl diamines (2a-b) on reaction synthesize Schiff's bases 3a-h. These compounds on reduction with NaBH4 in dry methanol yielded 2,2′-((alkyl-1,2-diylbis (azanediyl)) bis(methylene))disubstituted phenol, 4a-h in good yield. The preferable 1,2-bis(6-substituted-2 H -benzo[ e ][1,3]oxazin-3(4 H)-yl)ethanes, 5a-h formed when the compounds 4a-h undergo an internal Mannich reaction with formaldehyde. Different spectroscopic methods prove the formation of all the compounds. The compounds 3 g, 4 g, 5c, and 5 g showed excellent antibacterial activity against S. aureus, E. coli, S. Typhi, and B. subtilis , antifungal activity against A. flavus, C. Albicans, A. niger, and C. oxysporum with MIC values of 6.25 µg/ml and anti-TB activity against M. tuberculosis for which is equivalent to the standard drug. Furthermore, studies on the antioxidant activity of the compounds 3b, 3c, 3 g, 4c, 5b, and 5f revealed that they have excellent antioxidant activity. To comprehend the electronic behavior of compound 5e, Density Functional Theory estimations at the DFT/B3LYP level via 6–31G++ (d, p) replicate the structure and geometry. The first-order hyperpolarizability calculation finds the non-linear visual feature of compound 5e. Finally, HOMO and LUMO analysis were used for the charge transfer interface between the structures. Against Cytochrome c Peroxidase (2 × 08), the compounds 3c and 4c exhibited good docking properties in Molecular docking studies. [Display omitted] [ABSTRACT FROM AUTHOR]

CATALYSTS, CYCLOHEXENE, ORGANIC chemistry, CHEMICAL reactions, CERIUM oxides, and CATALYTIC oxidation

• Ultrasonic impregnation of Co, Ce or Co-Pd active phase on γ-Al 2 O 3 is presented. • Ultrasounds influences higher metal distribution and smaller crystallites and grains. • Characterization methods indicate Co as Co 3 O 4 or CoAl 2 O 4 and Ce in the form of CeO 2. • The addition of Pd to Co/γ-Al 2 O 3 do not influence the status of cobalt. • Ultrasonic irradiation increases surface area and decreases pore size and pore volume. The oxidation of cyclohexene belongs to the most important reactions in organic chemistry and leads to the production of the precursors for surfactants, polymers, agrochemicals, and drugs. So far, however, due to a complex reaction mechanism, it was hard to find the catalyst of satisfactory properties. Attractive catalysts in this reaction could be sonochemically prepared Co, Ce, and Pd containing γ-Al 2 O 3 , which is the object of the undertaken research. What is more, this combination of metals in the oxide system has not been studied. The analysis of catalytic performance indicated that all studied catalysts were active in the catalytic oxidation of cyclohexene. For metal-containing alumina (Me=Co, Ce, Pd), the conversion of cyclohexene was 61–84%. The best catalyst was Co 5 Ce 5 /γ-Al 2 O 3 s , prepared via the sonochemically-assisted procedure. It was also shown that the application of ultrasonic irradiation during the preparation of samples enhanced metal distribution over alumina support, resulted in smaller crystallites of prepared materials, and caused higher surface area with simultaneous smaller both pore size and pore volume in comparison with counterparts prepared via the standard procedure. XRD, Ra, and DR..-UV–vis spectroscopies indicated the coexistence of Co as Co 3 O 4 and CoAl 2 O 4 spinel, however, Ce was found in the form of CeO 2. The addition of Pd to Co/γ-Al 2 O 3 did not influence the status of cobalt. [Display omitted] [ABSTRACT FROM AUTHOR]

MEASUREMENT of viscosity, DIFFUSION coefficients, STABILITY constants, AQUEOUS solutions, ORGANIC chemistry, TEMPERATURE measurements, CARBONATE minerals, and GLYCERIN

[Display omitted] • Diffusivity, density and viscosity for GC in H 2 O were measured at 283.15 K–313.15 K. • The activation energy and the hydrodynamic parameters were calculated. • Data analysis suggests the formation of hydrogen bonded GC-GC dimers. • Formation constant, diffusivity and hydrodynamic radius were calculated for the dimer. Glycerol Carbonate (4-hydroxymethyl-2-oxo-1,3-dioxolane, GC) is an emerging green reactant for many organic chemistry applications. GC popularity stems from its high reactivity, which makes it attractive for many chemical transformations and for its easy synthesis from glycerol, a byproduct of biodiesel production. While extensive literature covers the synthesis and chemical reactivity of GC, its transport properties are poorly studied, especially in water. Here, we measured for the first time the diffusion coefficient of GC in water in the temperature range 283.15–313.15 K and for concentrations up to 0.1 M. By taking advantage of the Taylor Dispersion Analysis (TDA) we found D 0 = 9.53 ± 0.06 × 10 - 10 m2/s at 298.15 K and an activation energy for the diffusion process E a = 3.74 ± 0.09 kcal/mol. Density and dynamic viscosity were also measured in the same temperature interval to calculate the hydrodynamic radius of GC. Experimental data helped in assessing the structure of GC aggregates formed in aqueous solutions and provided an estimation of the equilibrium constant for the dimer formation. Our findings can be useful for studying the fate of GC in the environment and to improve its use for applications in aqueous media. [ABSTRACT FROM AUTHOR]

FATTY acids, ORGANIC chemistry, OLEIC acid, DIFFRACTION patterns, INDUSTRIAL capacity, INORGANIC compounds, and X-ray diffraction

The preparation of a novel crystalline fatty lambda-zirconium phosphate oleate, λ- ZrPO 4 (OH) 0.18 (C 18 H 33 O 2) 0 · 82 (CH 3) 2 SO, is reported in this research work. The material is characterized and formulated on the basis of its elemental, TGA, FT-IR and X-ray analyses. The X-ray diffraction pattern reveals that the interlayer distance of our new fatty material is heavily increased (2.96 nm) in comparison with that of the pristine λ-ZrP (1.02 nm). Therefore, this material could have potential applications in the field of intercalation chemistry of large organic and inorganic guests. • Chloride ligand of pure λ-ZrP can be easily exchanged with fatty acids. • Oleic acid leading to the formation of novel λ-type fatty solid material. • λ-ZrP materials could be functionalized with other aliphatic and aromatic fatty acids. • λ-ZrP and these fatty solid materials could have potential industrial applications. [ABSTRACT FROM AUTHOR]

ONLINE education, DISTILLATION, LEARNING strategies, PEERS, and ORGANIC chemistry

Model distillation is an effective way to let a less-parameterized student model learn the knowledge of a large teacher model. It requires a well-trained and high-performance model in advance, which limits the application of the deep model in some multimedia devices. However, the powerful teacher is not always available. Given this, some researchers propose a strategy of learning from each student model to replace the traditional teacher–student learning paradigm. Although this way has achieved good results recently, the simple mutual learning between student networks is easy to reach saturation earlier. In this work, we propose a smarter mutual learning method called Smarter Peer Learning (SPL) for online knowledge distillation, which puts forward a weight evaluation mechanism to build a virtual teacher and a novel online distillation framework. The ensemble teacher is constructed by combining the output of student networks through the calculated weight so that students will learn more from the better performance peers in the next stage of the learning. The experiments show that our SPL can train more efficient students than some existing advanced methods by applying various backbone networks to CIFAR-10, CIFAR-100, and Tiny-ImageNet datasets. [ABSTRACT FROM AUTHOR]

TERTIARY amines, IMINES, BIOACTIVE compounds, ORGANIC chemistry, AMINES, ENOLS, and NUCLEOPHILES

Chiral α-tertiary amines, a motif present in α,α-disubstituted α-amino acids, in a wide range of natural products, and many drugs and drug candidates, are important targets in organic chemistry. Among the possible strategies, 1,2-addition to chiral N -sulfinyl-ketimines is one of the best routes to form chiral α-tertiary amines with a high level of stereoselectivity. In this review, we focus first on the addition of organometallic reagents or other nucleophiles as enols or ylides to chiral N -sulfinylketimines. Then secondly we cover a selection of applications of these additions in the synthesis of valuable biologically active compounds. 1 Introduction 2 1,2-Addition Reaction Methodologies 2.1 Organolithium Reagent Additions 2.2 Grignard Additions 2.3 Organozinc Reagent Additions 2.4 Organoindium Reagent Additions 2.5 Organoboron Reagent Additions 2.6 Strecker Reactions 2.7 Palladium-Catalyzed Reactions 2.8 Enols, Enolates, and Other Deprotonated Reagent Additions 2.9 Ylide Additions 2.10 Heteroatom Nucleophiles 2.11 Miscellaneous Reactions 3 Applications to the Synthesis of Biologically Active Molecules 4 Conclusions [ABSTRACT FROM AUTHOR]

ORGANIC chemistry, RADICAL anions, ACENES, MATERIALS science, and X-ray diffraction

Boron‐embedded heteroacenes (boraacenes) have attracted enormous interest in organic chemistry and materials science. However, extending the skeleton of boraacenes to higher acenes (N≥6) is synthetically challenging because of their limited stability under ambient conditions. Herein, we report the synthesis of boron‐embedded heptacene (DBH) and nonacene (DBN) as the hitherto longest boraacenes. The former is highly stable (even after 240 h in tetrahydrofuran), while the latter is air‐sensitive with the half‐life (t1/2) of 11.8 min. The structures of both compounds are verified by single‐crystal X‐ray diffraction, revealing a linear backbone with an antiaromatic C4B2 core. Photophysical characterizations associated with theoretical calculations indicate that both compounds exhibit highly efficient anti‐Kasha emissions. Remarkably, the air‐stable DBH manifests an ultrahigh photoluminescence quantum yield (PLQY) of 98±2 % and can be chemically reduced to its radical anion and dianion states, implying the value of boron‐doped higher acenes as novel functional materials. [ABSTRACT FROM AUTHOR]

CHELATION, AMINATION, CATALYSTS, ORGANIC chemistry, PHARMACEUTICAL chemistry, and OXIDATION states

Comprehensive Summary: Nitrogen‐containing compounds are ubiquitously found in the fields of organic chemistry, pharmaceuticals, agrochemicals, medicinal chemistry and functional materials. The C—H bond amination reaction is one of the most straightforward protocols in the C—N bond formation, showing "step" and "atomic" economy. As a catalyst for C—H amination reaction, copper exhibits its unique catalytic properties due to easily accessible oxidation states. The research progress of copper‐catalyzed C—H amination in recent years is summarized. At the same time, reaction mechanisms are also briefly described in representative aminations to provide insights for the development prospects of highly practical and more environmentally benign processes. [ABSTRACT FROM AUTHOR]

RAPID eye movement sleep, SOLAR cells, CYCLOHEXANE, PREFRONTAL cortex, and ORGANIC chemistry

The article focuses on several research concerning rapid eye movement (REM) sleep, solar cells and cyclohexane. Topics discussed include emotional memories consolidated during rapid eye movement (REM) sleep in prefrontal cortex, solar spectrum allowed by tandem solar cell to be used and role of analysis of disubstituted cyclohexanes in development of organic chemistry.

Lignin is the largest natural source of functionalized aromatics on the planet, therefore exploiting its inherent structural features for the synthesis of aromatic products is a timely and ambitious goal. While the recently developed lignin depolymerization strategies gave rise to well-defined aromatic platform chemicals, the diversification of these structures, especially toward high-end applications is still poorly addressed. Molecular motors and switches have found widespread application in many important areas such as targeted drug delivery systems, responsive coatings for self-healing surfaces, paints and resins or muscles for soft robotics. They typically comprise a functionalized aromatic backbone, yet their synthesis from lignin has not been considered before. In this contribution, we showcase the synthesis of a novel light-driven unidirectional molecular motor from the specific aromatic platform chemical 4-(3-hydroxypropyl)-2,6-dimethoxyphenol (dihydrosynapyl alcohol) that can be directly obtained from lignocellulose via a reductive catalytic fractionation strategy. The synthetic path takes into account the principles of green chemistry and aims to maintain the intrinsic functionality of the lignin-derived platform molecule. [ABSTRACT FROM AUTHOR]

LIFE sciences, ORGANIC synthesis, BIOLOGICAL networks, INDUSTRIAL chemistry, ASSOCIATION (Chemistry), and ORGANIC chemistry

We should also remind ourselves that while synthetic organic chemistry has reached a high level of sophistication - often no longer being the bottleneck in drug discovery (c.f. preclinical biological activity translation into the clinical setting) - our synthetic chemistry capabilities are still far from being perfect. The Life Science sector is currently undergoing a revolutionary transformation - powered by the convergence of biology, technology and data-driven insights. Photoredox chemistry can also enable late-stage functionalization of various chemical modalities such as peptides as highlighted by Ruf et al.Riley and co-workers have combined photoredox catalysis with flow chemistry conditions and applied this protocol to a key carbon-nitrogen bond forming reaction in the synthesis of Entrectinib (Rozlytrek®). Synthetic chemistry will be a strong enabler of Life Science innovation and expand its reach significantly (exploring abiotic RNA/DNA, amino acids/peptides, protein drug conjugates, PROTACs in addition to classical small molecules). [Extracted from the article]

ORGANIC synthesis, LIFE sciences, CONVERGENT evolution, ORGANIC chemistry, and INDUSTRIAL chemistry

In this editorial, the future role of industrial organic chemistry in life science is discussed. B The Front Cover b illustrates the convergence of innovation in biology and digital technology. Organic chemistry is both a fundamental enabler of this transformation but also benefits from scientific breakthroughs in other scientific domains. [Extracted from the article]

CHEMICAL warfare agents, LIQUID chromatography-mass spectrometry, NERVE gases, and ORGANIC chemistry

Recently, the cases of Sergei and Yulia Skripal and of Alexei Navalny have attracted considerable public interest in acetylcholine esterase inhibitors in general, and Novichok agents in particular. The name "Novichok" is given to chemical warfare agents supposedly developed in the former Soviet Union between the 1970s and the 1990s, as a reaction to the British/American invention of VX agent. These three newcomer agents were synthesized much like VX, tabun, soman, and sarin, as unitary agents, meaning that the chemical structure is altered during production so that maximum potency occurs rapidly at the outset. In response, development of binary newcomer agents escalated at GosNIIOKhT, and in 1989 the first known binary newcomer agent, Novichok-5 was synthesized off the base structure of A-232 i " (for detailed references, see Chai et al. [2]). [Extracted from the article]

HYDROGENATION, ALKENES, DIOLEFINS, ORGANIC chemistry, SILYL enol ethers, LIGANDS, and CATALYSTS

Comprehensive Summary: Olefins are very easily accessible compounds which are both popular substrates in synthetic chemistry and good ligands in the organometallic complexes. This dual character makes olefins a rich source of chiral ligands and catalysts for asymmetric catalysis. Herein, we will briefly summarize our studies on the development of chiral diene ligands for transition‐metal catalyzed asymmetric reactions and chiral FLP catalysts for asymmetric metal‐free hydrogenations and hydrosilylations. Several acyclic chiral diene ligands as well as P/olefin and S/olefin hybrid ligands were developed for Rh or Pd‐catalyzed asymmetric reactions. With these ligands in hand, we further put forward a novel strategy for acquiring chiral FLP catalysts via the in situ hydroboration of chiral dienes with Piers' borane. These catalysts proved to be highly effective for asymmetric metal‐free hydrogenations and hydrosilylations of imines, silyl enol ethers, ketones, and aromatic N‐heterocycles. What is the most favorite and original chemistry developed in your research group? The development of acyclic dienes both as chiral ligands and as precursors of chiral FLP catalysts. How do you get into this specific field? Could you please share some experiences with our readers? When I started my independent research in 2008, chiral olefins belong to one novel ligand type. We got into the field with the thought of the simpler the better. This experience further led us to step into FLP catalysis. What is the most important personality for scientific research? Courage and persistence of doing something unique. What are your hobbies? Walking and playing cards. How do you keep balance between research and family? Life is not only research, but also family. You believe it, the balance is there. What is your favorite journal(s)? My favorite journal is Organic Letters, in which authors can publish their work rapidly and readers can browse the progress of organic chemistry comprehensively. [ABSTRACT FROM AUTHOR]

DIPHENYL, ENANTIOMERIC purity, DERACEMIZATION, ORGANIC chemistry, DIAMIDES, and NUCLEAR magnetic resonance spectroscopy

Chiral compounds with a 1,2‐diamine structure motif and their derivatives are of great interest in organic chemistry and are broadly used in asymmetric transformations, as chiral auxiliaries, (co)ligands, and ligand core structure. Here, we present a straightforward, diastereoselective synthesis for a diamide‐bridged biaryl ligand. The ring closing reaction of the racemic atropos biphenyl 6,6′‐dimethoxy‐[1,1′‐biphenyl]‐2,2′‐dicarboxylic acid with (R,R)‐diaminocyclohexane yields the diasteromerically and enantiomerically pure cyclic (Sax,R,R)‐BIPOL, which can be used as a versatile chiral ligand. By NMR spectroscopy, we observed the formation of intermolecular aggregates of the diamide‐bridged BIPOL with anhydrous DMSO‐d6. DFT calculations at the B3LYP/6‐31G* level of theory corroborate the high interconversion barrier for the biaryl axis of ΔGǂ = 148.7 kJ mol−1 and the favoured formation of (Sax,R,R)‐BIPOL as single stereoisomer. [ABSTRACT FROM AUTHOR]

In this article, we present fluorescent guanidiniocarbonyl-indoles as versatile oxo-anion binders. Herein, the guanidiniocarbonyl-indole (GCI) and methoxy-guanidiniocarbonyl-indole (MGCI) were investigated as ethylamides and compared with the well-known guanidiniocarbonyl-pyrrole (GCP) concerning their photophysical properties as well as their binding behavior towards oxo-anions. Hence, a variety of anionic species, such as carboxylates, phosphonates and sulfonates, have been studied regarding their binding properties with GCP, GCI and MGCI using UV-Vis titrations, in combination with the determination of the complex stoichiometry using the Job method. The emission properties were studied in relation to the pH value using fluorescence spectroscopy as well as the determination of the photoluminescence quantum yields (PLQY). Density functional theory (DFT) calculations were undertaken to obtain a better understanding of the ground-lying electronic properties of the investigated oxo-anion binders. Additionally, X-ray diffraction of GCP and GCI was conducted. We found that GCI and MGCI efficiently bind carboxylates, phosphonates and sulfonates in buffered aqueous solution and in a similar range as GCP (Kass ≈ 1000–18,000 M−1, in bis-tris buffer, pH = 6); thus, they could be regarded as promising emissive oxo-anion binders. They also exhibit a visible fluorescence with a sufficient PLQY. Additionally, the excitation and emission wavelength of MGCI was successfully shifted closer to the visible region of the electromagnetic spectrum by introducing a methoxy-group into the core structure, which makes them interesting for biological applications. [ABSTRACT FROM AUTHOR]

OPTICAL properties, DYE-sensitized solar cells, OPTOELECTRONICS, DENSITY functional theory, PHOTOLUMINESCENCE measurement, ALIZARIN, and DYES & dyeing

Optical properties of Alizarin dye for dye-sensitized solar cells were performed experimentally using transmittance and photoluminescence spectroscopies and confirmed theoretically using the density functional theory. The solvent effect of photoluminescence measurement was observed, and the strongest luminescence was 1.4E7 CPS at 437 nm. A widely investigated transmittance, focusing our attention on its optical properties in the visible and near-infrared regions. Broad absorbance from 400 nm to 600 nm was shown with two maximum peaks. The electronic properties such as HOMO and LUMO levels were computed via Gaussian software, as well as the estimation of the key photovoltaic parameters such as ΔG inject, ΔG reg , |V RP |, LHE, τ and V oc equal to −1.96 eV, 1.64 eV, 1.22 eV, 0.21, 11.39 ns and 1.26 V, respectively. The theoretical absorbance calculations of Alizarin dye are in good agreement with the experimental measurement, with a shift of 9 nm for the first absorbance peak and 2 nm for the second peak. The experimental and computational results confirm that Alizarin dye can be applied as a potential sensitizer for dye-sensitized solar cells. • Broad absorbance and strong photoluminescence of Alizarin dye. • Optimized geometry calculation and electronic properties by DFT and B3LYP/6-311G**. • Correlations between theoretical results and experimental data. • Theoretical and experimental justifications for the DSSC application of Alizarin. [ABSTRACT FROM AUTHOR]

QUINONE derivatives, MELTING points, INDOLE, THIN layer chromatography, and ORGANIC synthesis

12-Ethyl-6-methyliden-1,2,3,4,5,6-hexahydro-1,5-methanoazocino[4,3-b]indole-3-one (4) Methyllithium (10 mL, 3.0 M MeLi solution in THF) was added to a solution of compound B 3 b (1.5 g, 5.2 mmol) in 30 mL of anhydrous THF under a nitrogen atmosphere at 0 SP ° sp C and the mixture was stirred at 0 SP ° sp C for 1 h. The organic layer was dried over magnesium sulfate, filtered, and the solvent was evaporated to give an oil, which was purified by column chromatography (silica gel, ethyl acetate:acetone:triethylamine, 4:1:1). Finally, compound B 4 b was reduced with tris(triphenylphosphine)rhodium(I) carbonyl hydride in THF to give (±)-noruleine B 5 b in four steps, with an over-all yield of 41% and also obtained as yellow oil.[21],[22],[28] All of the component compounds in the preparative sequence were rigorously characterized (see Experimental section). The uleine alkaloids (Figure 1) have remarkable biological activities and have attracted much interest from synthetic organic chemists. [Extracted from the article]

DISSOLVED organic matter, ION mobility spectroscopy, ION cyclotron resonance spectrometry, ORGANIC chemistry, TIME-of-flight mass spectrometry, and EUTROPHICATION

• Eutrophication shaped DOM chemistry to a more aliphatic signature with lower isomeric complexity. • Eutrophication induced production of a red-shifted humic-like fluorescence. • This red-shifted humic-like fluorescence carries an aliphatic molecular signature. • Reed marsh introduced unique highly aromatic compounds to connected rivers. • Optical and molecular techniques are complimentary for DOM cycling study in coastal environments. Dissolved organic matter (DOM) plays a crucial role in the coastal carbon cycle. However, eutrophication-induced algal blooms and lateral transport from connected tidal marshes may significantly affect DOM cycling, which remains poorly understood. By combining a suite of bulk and optical techniques, and the Fourier transform ion cyclotron resonance mass spectrometry and ion mobility quadrupole time-of-flight mass spectrometry, we determined DOM concentration and composition along two typical river-estuary transects (namely Liao and Daliao rivers), Northeast China, with contrasting eutrophic state and distribution of tidal marshes. The Daliao River is characterized by a higher eutrophication degree and is surrounded with lower reed coverage than the Liao River. Compared to the Liao River, significantly higher dissolved organic carbon concentrations were observed in the Daliao River, where higher stable carbon isotope (δ13C) values and protein-like fluorescent components, characterized relatively higher autochthonous DOM. Further molecular analysis revealed higher peptide and sugar-like compounds but lower isomeric percentages of several molecular formulas in the Daliao River, suggesting higher molecular lability but lower isomeric complexity than the Liao River. Associations between optical and molecular signatures among all DOM samples revealed that a red-shifted humic-like C3 component was significantly correlated with molecular formulas with lower molecular weight and aromaticity, and higher H/C, indicating that C3 was likely a result of phytoplankton production coupled with further heterotrophic processing. Moreover, we found that reed marshes could introduce to both rivers a series of carboxylic-rich alicyclic compounds, highly unsaturated compounds, and polyphenols with high molecular weight and low H/C. This study suggests that eutrophication and reed marsh affect the DOM quality and can be a potential source of recalcitrant DOM compounds to coastal rivers and estuaries, which warrants further investigations considering the increasing worldwide eutrophication and sea-level rise in coastal delta environments. [Display omitted] [ABSTRACT FROM AUTHOR]

DENSITY functionals, ORGANIC chemistry, and CHEMICAL reactions

In this Communication, we assess a panel of 18 double-hybrid density functionals for the modeling of the thermochemical and kinetic properties of an extended dataset of 449 organic chemistry reactions belonging to the BH9 database. We show that most of DHs provide a statistically robust performance to model barrier height and reaction energies in reaching the "chemical accuracy." In particular, we show that nonempirical DHs, such as PBE0-DH and PBE-QIDH, or minimally parameterized alternatives, such as ωB2PLYP and B2K-PLYP, succeed to accurately model both properties in a balanced fashion. We demonstrate, however, that parameterized approaches, such as ωB97X-2 or DSD-like DHs, are more biased to only one of both properties. [ABSTRACT FROM AUTHOR]

ORGANIC compounds, ORGANIC chemistry, COMPLEX compounds, PHOSPHINE oxides, ALDEHYDES, and PENTANE

[Display omitted] H-phosphonates, H-phosphinates and secondary phosphine oxides are versatile reagents for the construction of complex phosphoryl compounds. Their decade advances in three-component reactions were recorded in this article. Reactions with bicyclo[1.1.1]pentane, alkenes, alkynes, aldehydes, imines, S, Se, et al will be discussed. In this review, we systematically summarized the applications of these P(O)-H compounds in organic synthetic chemistry, and their mechanisms were also discussed. [ABSTRACT FROM AUTHOR]

WOMEN'S volleyball and ORGANIC chemistry

Under aprotic conditions, the stoichiometric reaction of N‐heterocyclic carbenes (NHCs) such as imidazolidin‐2‐ylidenes with aldehydes affords Breslow Intermediates (BIs), involving a formal 1,2‐C‐to‐O proton shift. We herein report kinetic studies (NMR), complemented by DFT calculations, on the mechanism of this kinetically disfavored H‐translocation. Variable time normalization analysis (VTNA) revealed that the kinetic orders of the reactants vary for different NHC‐to‐aldehyde ratios, indicating different and ratio‐dependent mechanistic regimes. We propose that for high NHC‐to‐aldehyde ratios, the H‐shift takes place in the primary, zwitterionic NHC‐aldehyde adduct. With excess aldehyde, the zwitterion is in equilibrium with a hemiacetal, in which the H‐shift occurs. In both regimes, the critical H‐shift is auto‐catalyzed by the BI. Kinetic isotope effects observed for R‐CDO are in line with our proposal. Furthermore, we detected an H‐bonded complex of the BI with excess NHC (NMR). [ABSTRACT FROM AUTHOR]

WOMEN'S volleyball and ORGANIC chemistry

BORANES, CATALYSTS, ORGANIC chemistry, CHEMICAL reactions, ALIPHATIC alcohols, GLYCOLS, and HIGH temperatures

Epoxide ring-opening is a key reaction in organic chemistry. We have previously shown that B(C 6 F 5) 3 , a strongly Lewis acidic arylborane, exhibited high rates and unusual selectivities for catalyzing the ring-opening of aliphatic epoxides with alcohols. Here we compare catalysts of the form B(C 6 H 5−X F X) 3 (x = 5, 4, 3, and 0) and determine that moderately Lewis acidic arylboranes have higher regioselectivity, but slower rates in this reaction. At high temperatures, these arylboranes can also hydrolyze into inactive species. However, deactivation is suppressed in the presence of co-catalytic amounts of 1,2-propanediol, and DFT calculations suggest a role for arylborane-H 2 O-diol complexes. Thermal stabilization and regioselectivity enhancement by diol are both more pronounced for B(C 6 F 5) 3 than for less Lewis acidic B(C 6 HF 4) 3 and B(C 6 H 2 F 3) 3 catalysts. These results further demonstrate the catalytic relevance of H-bound networks of arylboranes and diols and enable their use at higher temperatures and greatly increased rates. [Display omitted] • Arylborane catalysts hydrolyze above 90 oC, which decreases rates and selectivity in epoxide ring-opening. • Co-catalytic glycol stabilizes the catalyst against hydrolytic decomposition for > 1 h, while also increasing selectivity. • Glycol-mediated stabilization is higher for more Lewis acidic catalysts such as tris(pentafluorophenyl)borane. [ABSTRACT FROM AUTHOR]

ORGANIC chemistry, CARBONYL group, ALDEHYDE derivatives, FUNCTIONAL groups, ELECTROSYNTHESIS, ANNULATION, and RING formation (Chemistry)

This review is based on the recent synthetic advancements of N‐tosylhydrazone under metal‐free conditions for the construction of nitrogen‐containing heterocycles. N‐Tosylhydrazones, an emerging building block in current organic chemistry offer moderate and flexible procedures through the carbene intermediates for the formation of C−C and carbon‐heteroatom bonds. N‐Tosylhydrazones are the derivatives of the aldehyde/keto group which act as carbene source, diazo precursors, and alternative of the respective carbonyl group. The key features of the N‐tosylhydrazone chemistry involve selective, controllable, one‐pot synthesis, good functional group tolerance, and metal‐free reactions with a wide scope of substrates. The current study includes mechanistic features, synthetic applications, substrate scope, limitation, and some additional reactions like electrosynthesis, regioselective, chemoselective, annulation, 1,3‐dipolar, and intermolecular cycloaddition. [ABSTRACT FROM AUTHOR]

PYRAZOLES, ORGANIC chemistry, AZETIDINE, PYRROLIDINE, PIPERIDINE, and PYRIMIDINES

An efficient approach to the multigram preparation of sp SP 3 sp -enriched fluorinated building blocks bearing protected azetidine, pyrrolidine, piperidine, or cyclohexanone moieties and transformations of these useful intermediates into the nitrogen heterocycles mentioned above are described. Keywords: Fluorine; Heterocycles; Pyrazoles; Pyrimidines; Synthetic methods EN Fluorine Heterocycles Pyrazoles Pyrimidines Synthetic methods 1 1 1 04/25/22 20220421 NES 220421 B The Front Cover b shows examples of fluoro-substituted pyrazoles and pyrimidines with saturated heterocyclic substituents - advanced building blocks for organic and medicinal chemistry synthesized by a group of chemists from Kyiv, Ukraine. Front Cover: Fluorine-Containing sp3-Enriched Building Blocks for the Multigram Synthesis of Fluorinated Pyrazoles and Pyrimidines with (Hetero)aliphatic Substituents (Eur. J. Org. [Extracted from the article]

HALOGENATION, VANADIUM, ORGANIC chemistry, TRANSITION metals, ORGANIC compounds, and BIOMIMETIC materials

• Catalytic mechanism of vanadium haloperoxidase (VHPO). • Synthetic investigation of VHPO. • Rationale biomimetic halogenation inspired by VHPO. • Summary of transition metal catalyzed biomimetic halogenation. • Reaction development, synthetic application, limitation and perspective. Organohalide is one of the most important and useful compounds in organic chemistry, broadly embodied in diverse bioactive molecules, organic materials and agrochemicals. Installation of halide to organic compound, in most cases, still relies on traditional electrophilic halogenation (e.g., utilizing Br 2 , I 2 and Cl 2), particularly in industrial production. Such process unavoidably generates undesired environmentally unfriendly by-products (e.g., HBr from Br 2). By contrast, in nature the haloperoxidase produces organic halides under mild condition in atom economy. But they suffer from high cost, limited substrate scope and specific working condition. The biomimetic halogenation inspired by nature, in theory, provides a potential solution for these limitations, serving as an alternative green halogenation approach. In this review, the author summarized the recent development of biomimetic halogenation inspired by vanadium dependent haloperoxidase (VHPO). Evident progress has been achieved in its functional mimics utilizing transition metal (TM) catalysts, including vanadate (V5+), molybdate (Mo6+), tungstate (W6+), and rhenate (Re7+). These robust biomimetic catalysts work efficiently under mild condition with broad substrate scope, and even afforded drug molecules in preparative scale. The challenges and opportunities for further development in this field were also discussed, along with the elucidation of VHPO's structure, functional mechanism and synthetic application. [ABSTRACT FROM AUTHOR]

NANOFIBERS, NERVOUS system regeneration, REGENERATION (Biology), NATURAL fibers, BONE cells, and EXTRACELLULAR matrix

Electrospun techniques are promising and flexible technologies to fabricate ultrafine fiber/nanofiber materials from diverse materials with unique characteristics under optimum conditions. These fabricated fibers/nanofibers via electrospinning can be easily assembled into several shapes of three-dimensional (3D) structures and can be combined with other nanomaterials. Therefore, electrospun nanofibers, with their structural and functional advantages, have gained considerable attention from scientific communities as suitable candidates in biomedical fields, such as the regeneration of tissues and organs, where they can mimic the network structure of collagen fiber in its natural extracellular matrix(es). Due to these special features, electrospinning has been revolutionized as a successful technique to fabricate such nanomaterials from polymer media. Therefore, this review reports on recent progress in electrospun nanofibers and their applications in various biomedical fields, such as bone cell proliferation, nerve regeneration, and vascular tissue, and skin tissue, engineering. The functionalization of the fabricated electrospun nanofibers with different materials furnishes them with promising properties to enhance their employment in various fields of biomedical applications. Finally, we highlight the challenges and outlooks to improve and enhance the application of electrospun nanofibers in these applications. [ABSTRACT FROM AUTHOR]

PYRAZOLES, ORGANIC chemistry, INDUSTRIAL chemistry, SMALL molecules, CLEAN energy, and AZOLES

Indazole and pyrazole are renowned as a prodigious class of heterocycles having versatile uses in medicinal as well as industrial chemistry. Considering sustainable approaches, recently, photocatalysis has become an indispensable tool in organic chemistry due to its application for the activation of small molecules and the use of a clean energy source. In this review, we have highlighted the use of metal-based photocatalysts, organic photoredox catalysts, energy transfer photocatalysts and electron-donor–acceptor complexes in the functionalization of indazole and pyrazole. This perspective is arranged based on the types of functionalization reactions on indazole and pyrazole. A detailed discussion regarding the reaction mechanism of each reaction is given to provide a comprehensive guide to the reader. Finally, a summary of existing challenges and the future outlook towards the development of efficient photocatalytic methods for functionalization of these heterocycles is also presented. [ABSTRACT FROM AUTHOR]

ALLYL alcohol, TRANSITION metals, RARE earth metals, ALLYLIC alkylation, ALLYLIC amination, ORGANIC chemistry, CARBON-carbon bonds, and NATURAL products

The nucleophilic allylic substitutions have become one of the most powerful tools for the construction of carbon-carbon and carbon-heteroatom bonds in organic chemistry. This review focuses on the main previous reports dealing with the evolution of the direct nucleophilic substitutions of simple allylic alcohols or diversely functionalized ones (i.e., Morita-Baylis-Hillman alcohols) with 1,3-dicarbonyl compounds, under the catalysis of a variety of transition metals (Pd, Ir, Ru, Rh, Cu, Ni, Fe, Co, Au, Ag, Pt, W) and rare earth metals (Sc, La, Yb) complexes under activators-free conditions or in the presence of activators, as well as Lewis/Brønsted acids, and organocatalysts. In each synthetic process, a mechanistic aspect is proposed, along with a comparison of the observed regioselectivity in Pd-catalyzed allylic alkylations with that of other metals. Finally, numerous applications to the synthesis of complex molecules and natural products, are presented. [Display omitted] [ABSTRACT FROM AUTHOR]

ORGANIC synthesis, CATALYSIS, SUSTAINABLE chemistry, SULFOXIMINES, ORGANIC chemistry, and FUNCTIONAL groups

The S(VI) compounds, mainly sulfonamide functional groups are widely used in medicinal and agro-chemistry for almost a century. Other molecules with S(VI) centre, namely sulfones, sulfoximines, sulfonimidamides, sulfonimidates are presently receiving tremendous interest in several areas including medicinal and synthetic organic chemistry. Despite numerous methods following the traditional pathways have been developed to synthesize these molecules and their further organic transformations, currently, light driven photoredox catalytic techniques have occupied front row due to their close connections with green and sustainable chemistry. This review discusses the preparations and synthetic applications of S(VI) centre bearing molecules via photoredox catalysis in detail to date. [Display omitted] [ABSTRACT FROM AUTHOR]

HETEROCYCLIC compounds, ORGANIC chemistry, and COUPLING reactions (Chemistry)

Keywords: Arylation; Benzofuran; C-C coupling; Copper catalysis; Palladium catalysis EN Arylation Benzofuran C-C coupling Copper catalysis Palladium catalysis 1 1 1 04/07/22 20220405 NES 220405 B The Front Cover b shows Diana's Temple (an ancient roman temple enclosure) from the city of Evora, Portugal. Arylation, Benzofuran, C-C coupling, Copper catalysis, Palladium catalysis Several methods that afford such ring systems as the central platform of medicinal compounds are discussed in this review: especially medicinally relevant oxygen benzofused heterocycles by palladium and copper catalyzed C-X activation of halo arenes. [Extracted from the article]

QUANTUM dots, NONIONIC surfactants, ORGANIC synthesis, IONIC surfactants, SEMICONDUCTOR nanoparticles, ORGANIC semiconductors, and PHOSPHINES

Efficient conversion of light from short wavelengths to longer wavelengths using color conversion layers (CCLs) underpins the successful operation of numerous contemporary display and lighting technologies. Inorganic quantum dots, based on CdSe or InP, for example, have received much attention in this context, however, suffer from instability and toxic cadmium or phosphine chemistry. Organic nanoparticles (NPs), though less often studied, are capable of very competitive performance, including outstanding stability and water-processability. Surfactants, which are critical in stabilizing many types of nano-structures, have not yet been used extensively in organic NPs. Here we show the utility of surfactants in the synthesis and processing of organic NPs by thoroughly characterizing the effect of ionic and non-ionic surfactants on the properties of fluorescent organic NPs. Using this information, we identify surfactant processing conditions that result in nearly 100 % conversion of organic fluorophores into sub-micrometer particles, or nano-dots, with outstanding performance as CCLs. Such water dispersions are environmentally benign and efficiently convert light. They can be used for a range of fluorophores covering a full spectral gamut, with excellent color purity, including full-width at half-maximum (FWHM) values as low as 21 nm. Compared to inorganic (InP) reference CCLs, the organic nano-dot based CCLs show superior color conversion efficiency and substantially improved long-term stability. Compared to inorganic nanoparticles, organic nanoparticles aren't as well understood. Here the authors explore the use of surfactants to prepare organic semiconductor nanoparticles with outstanding photophysical properties. [ABSTRACT FROM AUTHOR]

CHEMICAL systems, ORGANIC chemistry, ASTROBIOLOGY, and ORGANIC compounds

The field of prebiotic chemistry has demonstrated that complex organic chemical systems that exhibit various life-like properties can be produced abiotically in the laboratory. Understanding these chemical systems is important for astrobiology and life detection since we do not know the extent to which prebiotic chemistry might exist or have existed on other worlds. Nor do we know what signatures are diagnostic of an extant or "failed" prebiotic system. On Earth, biology has suppressed most abiotic organic chemistry and overprints geologic records of prebiotic chemistry; therefore, it is difficult to validate whether chemical signatures from future planetary missions are remnant or extant prebiotic systems. The "biosignature threshold" between whether a chemical signature is more likely to be produced by abiotic versus biotic chemistry on a given world could vary significantly, depending on the particular environment, and could change over time, especially if life were to emerge and diversify on that world. To interpret organic signatures detected during a planetary mission, we advocate for (1) gaining a more complete understanding of prebiotic/abiotic chemical possibilities in diverse planetary environments and (2) involving experimental prebiotic samples as analogues when generating comparison libraries for "life-detection" mission instruments. [ABSTRACT FROM AUTHOR]

SMALL molecules, IMIDAZOLES, CHEMICAL synthesis, BORONIC acids, LIBRARIES, COUPLING reactions (Chemistry), and ANILINE

A series of novel 'drug-like' small molecules based on 1 H -benzo[ d ]imidazole derivatives bearing furan-2-yl, 4-piperidine and 5-aryl/aminoaryl substitutions were designed and synthesised. The key intermediate tert -butyl-4-(5-bromo-2-(furan-2-yl)-1 H -benzo[ d ]imidazol-1-yl)piperidine-1-carboxylate (5) was synthesised via sequential reaction starting from 4-bromo-1-fluoro-2-nitrobenzene (1). The 5-aryl-substituted molecular library was generated via Suzuki–Miyura coupling of tert -butyl-4-(5-bromo-2-(furan-2-yl)-1 H -benzo[ d ]imidazol-1-yl)piperidine-1-carboxylate (5) with various boronic acids while Buchwald coupling of 5 with various anilines generated the second molecular library of tert -butyl-4-(2-(furan-2-yl)-5-(arylamino)-1 H -benzo[ d ]imidazol-1-yl)piperidine-1-carboxylates. The structures of all the newly synthesised compounds were confirmed by spectral analysis. The optimised procedure gives easy access to two new molecular libraries of 1 H -benzo[ d ]imidazoles with operational simplicity and good yield. A series of novel 'drug-like' small molecules based on 1 H -benzo[ d ]imidazole derivatives bearing furan-2-yl, 4-piperidine and 5-aryl/aminoaryl substitutions were designed and synthesised. The optimised procedure gave easy access to two novel molecular libraries of 1 H -benzo[ d ]imidazoles with operational simplicity and good yield. [ABSTRACT FROM AUTHOR]

NUCLEIC acids, PEPTIDES, ORGANIC chemistry, CARBOHYDRATES, CONTROLLED drugs, and CONSTRUCTION materials

The last decade has witnessed the blooming of nucleic acids for therapeutic and diagnostic applications. In the present article, we describe the most important results from our group in this area covering the international context that surrounded this research. These include the study of modifications at the terminal and internal positions of siRNA duplexes to enhance nuclease resistance, increase loading of the antisense strand to RISC and avoid side effects such as activation of immune response and sense strand misloading. Then, we describe the design of novel lipid, carbohydrate and peptide conjugates to enhance cellular uptake. Finally, we describe the use of nanostructures for drug delivery and for the controlled deposition of matter on surfaces. We invite the readers to submerge into a highly interdisciplinary discipline that combines organic chemistry, biochemical assays, pharmacology issues as well as materials chemistry and structural studies in order to increase the applications of nucleic acids. [ABSTRACT FROM AUTHOR]

SULFOXIDES, ORGANIC chemistry, SULFIDES, PHOTOCATALYSIS, FUNCTIONAL groups, OXIDATION, NATURAL products, and PHOTOCHEMISTRY

Sulfoxides constitute one of the most important functional groups in organic chemistry found in numerous pharmaceuticals and natural products. Sulfoxides are usually obtained from the oxidation of the corresponding sulfides. Among various oxidants, oxygen or air are considered the greenest and most sustainable reagent. Photochemistry and photocatalysis is increasingly applied in new, as well as traditional, yet demanding, reaction, like the aerobic oxidation of sulfides to sulfoxides, since photocatalysis has provided the means to access them in mild and effective ways. In this review, we will summarize the photochemical protocols that have been developed for the oxidation of sulfides to sulfoxides, employing air or oxygen as the oxidant. The aim of this review is to present: i) a historical overview, ii) the key mechanistic studies and proposed mechanisms and iii) categorize the different catalytic systems in literature. [ABSTRACT FROM AUTHOR]

COPPER ions, METALLOPORPHYRINS, PORPHYRINS, ORGANIC chemistry, PHOTOTHERMAL conversion, and FLUORESCENCE

In present work, a fluorescent porphyrin organic cage sensor PTC-1(2H) for sensitively and selectively detecting divalent copper ion has been introduced. PTC-1(2H) contains the three metal-free units connected by chiral cyclohexanediamine, exhibiting a red-light emission with a broad band at the maximum 641 nm. Among the addition of various metal ions, the emission of PTC-1(2H) has been exclusively and seriously quenched by the addition of divalent copper ions, exhibiting a low limit of detection value of 6.3 nM. A crystal structure of cage with copper ion confirms the complexation of porphyrin N 4 cavity and metal ions, revealing the optimized bind position. The special cage structure exhibits the better sensing property than monomeric compound. In addition, a photothermal conversion performance of PTC-1(Cu) has been discovered. These results further enrich the chemistry of porous organic cages. A porphyrin organic cage has been used as fluorescence sensor for sensitively and selectively detecting divalent copper ions. [Display omitted] • A fluorescent porphyrin organic cage sensor PTC-1(2H) for sensitively and selectively detecting divalent copper ion has been introduced. • PTC-1(2H) exhibits a low limit of detection value of 6.3 nM for Cu2+. • A crystal structure of PTC-1(2H) with copper ion confirms the complexation of porphyrin N 4 cavity and metal ions, revealing the optimized bind position. • A photothermal conversion performance of PTC-1(Cu) has been discovered. [ABSTRACT FROM AUTHOR]

CHEMISTRY education, ORGANIC chemistry, STUDENT financial aid, STUDENT engagement, and CONSTRUCTION projects

Teaching chemistry remains a profoundly challenging activity. This paper arises from reflection on the challenges of creating meaningful assessments. Herein a simple framework to assist in making more visible the different kinds of knowledge required for mastery of chemistry is described. Building from a realist foundation the purpose of this paper is to lay the intellectual scaffolding for the framework. By situating the framework theoretically, it is intended to highlight the value of engaging with philosophy for the project of knowledge building in chemistry. Use of this framework has laid bare some significant limitations to the ways in which organic chemistry has been assessed. Making the visible to students aids in their engagement with knowledge and for a small minority has developed their understanding of science more generally. The framework provides a simple, easily usable tool for the evaluation of chemistry assessments. [ABSTRACT FROM AUTHOR]

KNOWLEDGE representation (Information theory), DISTILLATION, KNOWLEDGE transfer, LEARNING, GENE regulatory networks, ONLINE education, and ORGANIC chemistry

Knowledge distillation provides an effective way to transfer knowledge via teacher-student learning, where most existing distillation approaches apply a fixed pre-trained model as teacher to supervise the learning of student network. This manner usually brings in a big capability gap between teacher and student networks during learning. Recent researches have observed that a small teacher-student capability gap can facilitate knowledge transfer. Inspired by that, we propose an evolutionary knowledge distillation approach to improve the transfer effectiveness of teacher knowledge. Instead of a fixed pre-trained teacher, an evolutionary teacher is learned online and consistently transfers intermediate knowledge to supervise student network learning on-the-fly. To enhance intermediate knowledge representation and mimicking, several simple guided modules are introduced between corresponding teacher-student blocks. In this way, the student can simultaneously obtain rich internal knowledge and capture its growth process, leading to effective student network learning. Extensive experiments clearly demonstrate the effectiveness of our approach as well as good adaptability in the low-resolution and few-sample scenarios. [ABSTRACT FROM AUTHOR]

ORGANIC synthesis, ORGANIC chemistry, PHENOL oxidase, CAFFEIC acid, INDUSTRIAL chemistry, LACCASE, BIOACTIVE compounds, and DOSAGE forms of drugs

Laccases (Lac) and tyrosinases (TYR) are mild oxidants with a great potential in research and industry. In this work, we review recent advances in their use in organic synthesis. We summarize recent examples of Lac-catalyzed oxidation, homocoupling and heterocoupling, and TYR-catalyzed ortho-hydroxylation of phenols. We highlight the combination of Lac and TYR with other enzymes or chemical catalysts. We also point out the biological and pharmaceutical potential of the products, such as dimers of piceid, lignols, isorhamnetin, rutin, caffeic acid, 4-hydroxychalcones, thiols, hybrid antibiotics, benzimidazoles, benzothiazoles, pyrimidine derivatives, hydroxytyrosols, alkylcatechols, halocatechols, or dihydrocaffeoyl esters, etc. These products include radical scavengers; antibacterial, antiviral, and antitumor compounds; and building blocks for bioactive compounds and drugs. We summarize the available enzyme sources and discuss the scalability of their use in organic synthesis. In conclusion, we assume that the intensive use of laccases and tyrosinases in organic synthesis will yield new bioactive compounds and, in the long-term, reduce the environmental impact of industrial organic chemistry. [ABSTRACT FROM AUTHOR]

BIOMOLECULES, BIOSYNTHESIS, BIOMIMETIC synthesis, ORGANIC chemistry, BIOLOGICAL systems, NANOBIOTECHNOLOGY, BIOCONJUGATES, and NUCLEIC acids

A post-nanotechnology concept has been assigned to an emerging concept, nanoarchitectonics. Nanoarchitectonics aims to establish a discipline in which functional materials are fabricated from nano-scale components such as atoms, molecules, and nanomaterials using various techniques. Nanoarchitectonics opens ways to form a more unified paradigm by integrating nanotechnology with organic chemistry, supramolecular chemistry, material chemistry, microfabrication technology, and biotechnology. On the other hand, biological systems consist of rational organization of constituent molecules. Their structures have highly asymmetric and hierarchical features that allow for chained functional coordination, signal amplification, and vector-like energy and signal flow. The process of nanoarchitectonics is based on the premise of combining several different processes, which makes it easier to obtain a hierarchical structure. Therefore, nanoarchitectonics is a more suitable methodology for creating highly functional systems based on structural asymmetry and hierarchy like biosystems. The creation of functional materials by nanoarchitectonics is somewhat similar to the creation of functional systems in biological systems. It can be said that the goal of nanoarchitectonics is to create highly functional systems similar to those found in biological systems. This review article summarizes the synthesis of biomimetic and biological molecules and their functional structure formation from various viewpoints, from the molecular level to the cellular level. Several recent examples are arranged and categorized to illustrate such a trend with sections of (i) synthetic nanoarchitectonics for bio-related units, (ii) self-assembly nanoarchitectonics with bio-related units, (iii) nanoarchitectonics with nucleic acids, (iv) nanoarchitectonics with peptides, (v) nanoarchitectonics with proteins, and (vi) bio-related nanoarchitectonics in conjugation with materials. [ABSTRACT FROM AUTHOR]

ALCOHOL oxidation, PHOTOCATALYTIC oxidation, BENZYL alcohol, METHYLAMMONIUM, ELECTRON paramagnetic resonance, ORGANIC chemistry, PEROVSKITE, and AIR conditioning

[Display omitted] • Lead-free perovskite materials as an eco-friendly photocatalyst. • Mild conditions under air atmosphere and UV–vis irradiation. • Remarkable performance with 96% conversion and 94% selectivity. Selective oxidation of alcohols to the corresponding aldehydes constitutes a great challenge in organic and green chemistry, which typically requires environmentally unfriendly oxidants/catalysts or relatively harsh conditions (high temperature & pressure). Herein, we report an eco-friendly perovskite-based photocatalyst, in which all-inorganic perovskite Cs 3 Sb 2 Br 9 microcrystals with high crystallinity were prepared using a facile antisolvent method at various temperatures. For the photocatalytic oxidation of benzyl alcohol, the Cs 3 Sb 2 Br 9 microcrystal photocatalysts exhibited up to 77% conversion and 88% selectivity toward benzaldehyde under oxygen atmosphere and visible-light illumination. More significantly, the comparative experimental results in air were close to those in oxygen, with the observation of 96% conversion and 94% selectivity for the optimized conditions under air atmosphere. Notably, the conversion of our best-performing photocatalyst was 32 and 6.4 times higher than that of the lead-based CsPbBr 3 and FAPbBr 3 (FA: formamidinium) perovskites, respectively. Furthermore, the underlying photocatalytic oxidation mechanism was proposed by the electron spin resonance (ESR) and the controlled experiments using specific scavengers. This study sheds light on promising new photocatalytic applications of the lead-free metal halide perovskites. [ABSTRACT FROM AUTHOR]

In the Sharpless asymmetric epoxidation of chiral secondary allylic alcohols, one substrate enantiomer is predominantly converted to the anti‐epoxy alcohol. We herein report the first highly syn‐selective epoxidation of terminal allylic alcohols using a titanium salalen complex as catalyst, at room temperature, and aqueous hydrogen peroxide as oxidant. With enantiopure terminal allylic alcohols as substrates, the epoxy alcohols were obtained with up to 98 % yield and up to >99 : 1 dr (syn). Catalyst loadings as low as 1 mol % can be applied without eroding the syn‐diastereoselectivity. Modification of the allylic alcohol to an ether does not affect the diastereoselectivity either [>99 : 1 dr (syn)]. Inverting the catalyst configuration leads to the anti‐product, albeit at lower dr (ca. 20 : 1). The synthetic potential is demonstrated by a short, gram‐scale preparation of a tetrahydrofuran building block with three stereocenters, involving two titanium salalen catalyzed epoxidation steps. [ABSTRACT FROM AUTHOR]

ELECTRONIC materials, MOIETIES (Chemistry), ORGANIC chemistry, and CATALYSTS

In recent years, benzimidates and benzamidines have received tremendous importance as starting materials owing to their electronic properties and high reactivity. Their application as directing groups for constructing biologically active molecules has been a hot topic of discussion. Because of the presence of nucleophilic nitrogen in both these moieties, they can easily provide a co‐ordinating site to catalysts to form metallocyclic complexes which activate the inert Csp2−H bond thereby producing desired N‐heterocycles. In this review, we have summarized the developments in ortho‐functionalization of benzimidates and benzamidines using several coupling partners. Reaction mechanisms of protocols, their substrate versatility and limitations of those procedures along with their uses have also been addressed. [ABSTRACT FROM AUTHOR]

CONTRAST media, ORGANIC chemistry, ACOUSTIC imaging, POSITRON emission tomography, MAGNETIC resonance imaging, PHOTOACOUSTIC spectroscopy, and INFRARED absorption

Optical imaging, especially fluorescence and photoacoustic imaging, is a non‐invasive imaging approach with high spatial and temporal resolution and high sensitivity, compared to positron emission tomography (PET) or magnetic resonance imaging (MRI). Due to the merits of imaging using the second near‐infrared (NIR‐II) window, like deeper penetration depth, high signal‐to‐noise ratio, high resolution, and low tissue damage, researchers have devoted great effort to developing contrast agents with NIR‐II absorption or emission. In this Review, we summarize recently developed organic luminescent and photoacoustic materials, ranging from small molecules to conjugated polymers. Then, we systematically introduce engineering strategies and describe the imaging performance classified by the skeleton cores. Finally, we elucidate the challenges and prospects of these NIR‐II organic dyes for potential clinical applications. We expect our summary can inspire researchers to expand the spectrum of NIR‐II contrast agents for diverse bioapplications. [ABSTRACT FROM AUTHOR]

BENZOXAZINES, PALLADIUM, PALLADIUM catalysts, ORGANIC chemistry, OXIDES, and OXYGEN in the blood

Direct activation of sp2 C–H bonds by a palladium catalyst has received significant attention in organic chemistry. However, most of these C–H activation reactions are carried out in hazardous solvents. Herein we report a novel solvent-free direct sp2 C–H bond functionalization (oxygenation) method using Pd(II)/Al2O3 catalysis of oxo-benzoxazine derivatives with good to excellent yields, and demonstrate its application in the synthesis of pharmaceutically important compounds. [ABSTRACT FROM AUTHOR]

CHEMICAL stability, FURAZANS, HYDROGEN bonding, BENZENE, MATERIALS science, ORGANIC chemistry, and MOLECULAR structure

The article presents a study which explores about the energy peak of benzenes with enhanced chemical stability. It mentions that structurally diverse benzene derivatives that can be generated by replacing the six hydrogen atoms with functional substituents. It discusses that increase in the number of nitro groups in the benzene ring usually results in lower chemical stability.

NATURAL products, ORGANIC chemistry, HETEROCYCLIC compounds, RING-opening reactions, SYNTHETIC products, ORGANIC synthesis, and RING formation (Chemistry)

Construction of benzo‐fused heterocycles, specifically which have one or more sp3 stereogenic carbon atoms on the heterocyclic ring, by intramolecular ring‐opening cyclization of epoxides with O‐ and N‐nucleophiles is a powerful synthetic tool in organic synthesis. In this Review, we analyze the efficiency of such a heterocyclization approach in natural product synthesis and synthetic methodologies published since the year 2000. In addition to briefly discussing the synthetic methods of accessing the requisite epoxide substrates, important aspects of the subsequent cyclization reaction, such as reaction conditions, endo‐ versus exo‐regioselectivity, protecting or functional group compatibility, and enantio‐ and distereoselectivity are surveyed. Although the literature of organic chemistry in the last four decades has witnessed a large number of reviews/book chapters on the epoxide ring‐opening chemistry, the title topic has never been reviewed. Herein, we have systematized it as a dedicated review for the first time. [ABSTRACT FROM AUTHOR]

INORGANIC chemistry, ORGANIC chemistry, CROWN ethers, SMALL molecules, BRONSTED acids, and COORDINATES

This tutorial review showcases recent (2015–2021) work describing ligand construction as it relates to the design of secondary coordination spheres (SCSs). Metalloenzymes, for example, utilize SCSs to stabilize reactive substrates, shuttle small molecules, and alter redox properties, promoting functional activity. In the realm of biomimetic chemistry, specific incorporation of SCS residues (e.g., Brønsted or Lewis acid/bases, crown ethers, redox groups etc.) has been shown to be equally critical to function. This contribution illustrates how fundamental advances in organic and inorganic chemistry have been used for the construction of such SCSs. These imaginative contributions have driven exciting findings in many transformations relevant to clean fuel generation, including small molecule (e.g., H+, N2, CO2, NOx, O2) reduction. In most cases, these reactions occur cooperatively, where both metal and ligand are requisite for substrate activation. [ABSTRACT FROM AUTHOR]

ENERGY consumption, ELECTROCHEMISTRY, ORGANIC chemistry, ORGANIC electrochemistry, and ATOMS

Visible-light photoredox catalysis has been regarded as an extremely powerful tool in organic chemistry, bringing the spotlight back to radical processes. The versatility of photocatalyzed reactions has already been demonstrated to be effective in providing alternative routes for cross-coupling as well as multicomponent reactions. The photocatalyst allows the generation of high-energy intermediates through light irradiation rather than using highly reactive reagents or harsh reaction conditions. In a similar vein, organic electrochemistry has experienced a fruitful renaissance as a tool for generating reactive intermediates without the need for any catalyst. Such milder approaches pose the basis toward higher selectivity and broader applicability. In photocatalyzed and electrochemical multicomponent reactions, the generation of the radical species acts as a starter of the cascade of events. This allows for diverse reactivity and the use of reagents is usually not covered by classical methods. Owing to the availability of cheaper and more standardized photo- and electrochemical reactors, as well as easily scalable flow-setups, it is not surprising that these two fields have become areas of increased research interest. Keeping these in view, this review is aimed at providing an overview of the synthetic approaches in the design of MCRs involving photoredox catalysis and/or electrochemical activation as a crucial step with particular focus on the choice of the difunctionalized reagent. [ABSTRACT FROM AUTHOR]

A new class of polymeric hole‐transport materials (HTMs) are explored by inserting a two‐dimensionally conjugated fluoro‐substituted pyrene into thiophene and selenophene polymeric chains. The broad conjugated plane of pyrene and “Lewis soft” selenium atoms not only enhance the π–π stacking of HTM molecules greatly but also render a strong interaction with the perovskite surface, leading to an efficient charge transport/transfer in both the HTM layer and the perovskite/HTM interface. Note that fluorine substitution adjacent to pyrene boosts the stacking of HTMs towards a more favorable face‐on orientation, further facilitating the efficient charge transport. As a result, perovskite solar cells (PSCs) employing PE10 as dopant‐free HTM afford an excellent efficiency of 22.3 % and the dramatically enhanced device longevity, qualifying it among the best PSCs based on dopant‐free HTMs. [ABSTRACT FROM AUTHOR]

CUCURBITACEAE, ORGANIC chemistry, IONS, AZO compounds, AQUEOUS solutions, and NUCLEOPHILES

Aryl diazonium ions are known to be an important intermediate in the divergent synthesis of azo compounds and substituted aromatics. The presence of more than one electrophilic center in a diazonium ion could lead to undesirable side reactions during a synthesis. Herein, we report that the electrophilic α-carbon on a phenyl diazonium [PhN2]+ ion can be selectively deactivated upon host–guest complexation with cucurbit[7]uril (CB7) in aqueous media, achieving a ∼60-fold increase in the half-life of [PhN2]+. Notably, however, the electrophilic nitrogen of the encapsulated diazonium ion remains active towards diazo coupling with strong nucleophiles, allowing the formation of azo compounds using a two-month-old aqueous solution of [CB7–PhN2]+. Our supramolecular approach can open new possibilities for the reactive chemistry of organic molecules in aqueous media. [ABSTRACT FROM AUTHOR]

PHENOLS, PHENOL, HETEROCYCLIC compounds, ORGANIC chemistry, and WASTE minimization

Phenol derivatives are widespread as important building blocks in various pharmaceuticals, agrochemicals and materials. Modern economy requires development of "green" methodologies that improve the efficiency of their use and reduction of waste. One such method is the C−H/C−H cross‐coupling, also known as the cross‐dehydrogenative coupling reaction. In this review article, we have summarised the C−H/C−H cross‐coupling reactions of phenols with five‐ and six‐membered heterocyclic compounds, systemised methods of activation of phenol or coupling partner. We discuss these advances with the goal of motivating increased interest to develop novel methodologies in this field of organic chemistry. [ABSTRACT FROM AUTHOR]

DEEP learning, ARTIFICIAL intelligence, MACHINE learning, ORGANIC chemistry, RATE coefficients (Chemistry), and BIOCHEMICAL substrates

Retrosynthesis is at the core of organic chemistry. Recently, the rapid growth of artificial intelligence (AI) has spurred a variety of novel machine learning approaches for data-driven synthesis planning. These methods learn complex patterns from reaction databases in order to predict, for a given product, sets of reactants that can be used to synthesise that product. However, their performance as measured by the top-N accuracy in matching published reaction precedents still leaves room for improvement. This work aims to enhance these models by learning to re-rank their reactant predictions. Specifically, we design and train an energy-based model to re-rank, for each product, the published reaction as the top suggestion and the remaining reactant predictions as lower-ranked. We show that re-ranking can improve one-step models significantly using the standard USPTO-50k benchmark dataset, such as RetroSim, a similarity-based method, from 35.7 to 51.8% top-1 accuracy and NeuralSym, a deep learning method, from 45.7 to 51.3%, and also that re-ranking the union of two models' suggestions can lead to better performance than either alone. However, the state-of-the-art top-1 accuracy is not improved by this method. [ABSTRACT FROM AUTHOR]

ORGANIC chemistry and NOBEL Prize in Chemistry

The article reports that Elsevier BV data-update for ‘Updated science-wide author databases of standardized citation indicators' originated as a publicly available database of top-scientists based on citation metrics from Scopus. Topics include Field- and subfield-specific percentiles are also provided for all scientists; and Single Year list gives the current citation impact during the single calendar year 2020 and the Career list assesses scientists for career-long citation impact.

ORGANOCATALYSIS, ORGANIC chemistry, and NOBEL Prize in Chemistry

The article informs that News item by Santanu Mukherjee provided glimpses of two organic chemists, Benjamin List and David W. C. MacMillan, who shared the 2021 Nobel Prize in Chemistry, to the delight of organic chemistry enthusiasts.Topics include contributions to the origins and development of organocatalysis, it will be apt to remember and acknowledge the pioneering contributions ; and work on biomimetic catalysis also influenced the birth of structural biology and medicine field.

Efforts are underway to improve the diagnosis and treatment for neurological disorders like depression, anxiety, epilepsy, and schizophrenia. The G‐protein‐coupled receptors (GPCRs) 5‐HT7  receptor, the most recently identified member of 5‐HT receptor family dysregulation has an association with various central nervous system (CNS) disorders and its ligands have an edge as potential therapeutics. Here, we report the synthesis, characterization, and biological evaluation of diversely substituted methoxy derivatives of 2‐benzoxazolone arylpiperazine for targeting 5‐HT7 receptors. Out of all derivatives, only C‐2 substituted derivative, 3‐(4‐(4‐(2‐methoxyphenyl)piperazin‐1‐yl)butyl)benzoxazol‐2(3H)‐one/ABO demonstrate a high affinity for human 5‐HT7 receptors. [11C]ABO was obtained by O‐methylation of desmethyl‐precursor using [11C]CH3OTf in the presence of NaOH giving a high radiochemical yield of 25 ± 12% (decay‐corrected, n = 7) with stability up to 1.5 h postradiolabeling. In vitro autoradiography displays binding of [11C]ABO in accordance with 5‐HT7 distribution with a decrease of approximately 80% and 40% activity in the hippocampus and cerebellum brain region when administered with 10 µM cold ligand. Prefatory positron emission tomography scan results in Sprague‐Dawley (SD) rat brain revealed fast and high radioactivity build‐up in 5‐HT7 receptor‐rich regions, namely, the hippocampus (2.75 ± 0.16 SUV) and the cerebral cortex (2.27 ± 0.02 SUV) establishing selective targeting of [11C]ABO. In summary, these pieces of data designate [11C]ABO as a promising 5‐HT7 receptor ligand that can have possible roles in clinics after its further optimization on different animal models. [ABSTRACT FROM AUTHOR]

RHODIUM catalysts, PHOSPHINE, ALKYNES, PHOSPHINES, LIGANDS, ORGANIC chemistry, and PHOSPHORUS

Organophosphines are an important class of ligands widely used in organic chemistry. Although great progress has recently been made in the rapid construction of new phosphines through Rh- or Ru-catalyzed C–H bond functionalizations, synthetic access to more diverse phosphines remains a challenge. We describe an efficient process for the rhodium-catalyzed phosphorus(III)-directed hydroarylation of internal alkynes to generate various alkenylated and 2′,6′-dialkenylated biarylphosphines with high selectivity. A range of diverse alkynes and phosphines were effectively prepared with broad functional-group compatibility under the optimized conditions. In addition, the developed protocol can be extended to modify chiral phosphine ligands, providing enantioenriched alkenylated phosphines without erosion of the enantiomeric excess. [ABSTRACT FROM AUTHOR]

ORGANIC chemistry, CATALYST supports, CLASSICAL conditioning, LITERATURE reviews, SUSTAINABLE chemistry, and CARBON nanofibers

1,3‐Thiazolidines have attracted a lot of interest due to their biological and pharmaceutical properties. For this reason, their synthesis is very important. Nanotechnology, nowadays, plays an important role in organic chemistry. Nano compounds, todays, act as support and catalyst in organic transformations. This review focuses on the recent advances on the synthesis and applications of nanocatalyst and their applications for the synthesis of 1,3‐thiazolidines. The present review describes the literature reports for the period 2012 to 2021. These reported approaches were performed in the classical and nonclassical conditions, particularly recent reports includes protocols under a green condition such as using catalyst, green solvents, and solvent‐free conditions. [ABSTRACT FROM AUTHOR]

MOLECULAR crystals, NUMBERS of species, OPTICAL materials, ORGANIC synthesis, ORGANIC chemistry, and FUNCTIONAL groups

Substances can be divided into 0D to 3D species based on the number of repeating units (atom, ion, and molecule) and their arrangements in space (point, linear, layer, and solid). Discrete substances belong to 0D species, polymers are examples of 1D species, and molecular crystals are 3D species. Most of the substances belong to one of these species. On the other hand, those categorized into 2D species wherein the repeating units organize a layer are less explored. 2D species have a surface and edges. The incorporation of these structural features into a molecular design can realize multifunctionalized systems that are difficult to achieve by conventional organic synthesis. The development of 2D species is, therefore, the frontier of organic, inorganic, and polymer chemistry. Nanographenes (NGs) are suitable scaffolds for realizing 2D species due to several factors, such as chemical stability and oxygen‐containing functional groups on the surface and on the edge, allowing postsynthetic modifications. Our group has utilized NGs with tens of nanometers in diameters for developing 2D species. Carboxy groups on the edge enable us to install various substituents into NGs, offering NG‐based functional materials. These studies demonstrate that the integration of NGs with organic chemistry can widen the scope of their applications other than optical materials that are a main application of NGs. We introduce our recent studies on the development of NG‐based functional materials realized by postsynthetic modifications. We hope that this account will contribute to the development of the chemistry of 2D species. [ABSTRACT FROM AUTHOR]

NUCLEOPHILES, ORGANIC chemistry, and TEXT files

Invited for the cover of this issue is Jinbo Hu and co‐workers at Shanghai Institute of Organic Chemistry and Chongqing University. The image depicts TFBT (S‐(trifluoromethyl) benzothioate), which is easily synthesized using KF, as an inexpensive, bench‐stable and user‐friendly trifluoromethylthiolation reagent. Read the full text of the article at 10.1002/chem.202104395. [ABSTRACT FROM AUTHOR]

REACTION mechanisms (Chemistry), ORGANIC reaction mechanisms, NUCLEOPHILIC substitution reactions, and ORGANIC chemistry

Keywords: historic problem-oriented teaching method; reaction mechanisms in organic chemistry; nucleophilic substitution; reaction kinetics; experiment for school students; Historisch-problemorientierter Unterricht; Reaktionsmechanismen der organischen Chemie; Nukleophile Substitution; Reaktionskinetik; Schülerexperiment EN historic problem-oriented teaching method reaction mechanisms in organic chemistry nucleophilic substitution reaction kinetics experiment for school students DE Historisch-problemorientierter Unterricht Reaktionsmechanismen der organischen Chemie Nukleophile Substitution Reaktionskinetik Schülerexperiment 53 53 1 03/07/22 20220301 NES 220301 B Das Titelbild b zeigt im Hintergrund Christopher Ingold, Edward Hughes und Hilda Ingold (abgebildet mit Erlaubnis der Royal Society of Chemistry nach Chem. Historic problem-oriented teaching method, reaction mechanisms in organic chemistry, nucleophilic substitution, reaction kinetics, experiment for school students Pölloth, Häfner und Schwarzer erschließen in ihrem Beitrag die historische Erforschung von Reaktionsmechanismen durch einfache Experimente und einen I history lift i für den Schulunterricht. [Extracted from the article]

REACTION mechanisms (Chemistry), ELIMINATION reactions, ORGANIC chemistry, SUBSTITUTION reactions, ORGANIC reaction mechanisms, NUCLEOPHILIC substitution reactions, and TWENTIETH century

Organic chemistry (OC) appears to be an unstructured and confusing subject to many learners. Reaction mechanisms often seem to be an additional challenge rather than a helpful guideline. Comparable problems were also found for OC as a science at the beginning of the 20th century. One turning point was the systematic application of physical principles on organic reactions through Ingold and coworkers. Kinetic measurements implied for example that in nucleophilic substitution reactions the elimination of the leaving group and the attack of the nucleophile could either occur at the same time or stepwise. In this work the historic insights are made accessible for school lessons by easy experiments suitable for school students. A fictional audio diary of Hilda Ingold is proposed as a history lift to make learners realize that in principle different reaction pathways are possible for one reaction type. [ABSTRACT FROM AUTHOR]

SURFACE analysis, ACETAMIDE, HYDROGEN bonding, NUCLEOPHILIC reactions, CRYSTAL structure, DENSITY functional theory, and CHALCOGENS

N-(4-((3-Methyl-1,4-dioxo-1,4-dihydronaphthalen-2-yl)selanyl)phenyl)acetamide (5), C19H15NO3Se, was prepared in two steps from 4,4′-diselanediyldianiline (3) via reduction and subsequent nucleophilic reaction with 2-methyl-3-bromo-1,4-naphthalenedione, followed by acetylation with acetic anhydride. The cytotoxicity was estimated against 158N and 158JP oligodendrocytes and the redox profile was also evaluated using different in vitro assays. The technique of single-crystal X-ray diffraction is used to confirm the structure of compound 5. The enantiopure 5 crystallizes in space group P21 with Flack parameter 0.017 (8), exhibiting a chiral layered absolute structure. Molecular structural studies showed that the crystal structure is foremost stabilized by N-H···O and relatively weak C-H···O contacts between molecules, and additionally stabilized by weak C-H···π and Se···N interactions. Hirshfeld surface analysis is used to quantitatively investigate the noncovalent interactions that stabilize crystal packing. Framework energy diagrams were used to graphically represent the stabilizing interaction energies for crystal packing. The analysis of the energy framework shows that the interactions energies of and C-H···π and C-O···π are primarily dispersive and are the crystal's main important forces. Density functional theory (DFT) calculations were used to determine the compound's stability, chemical reactivity, and other parameters by determining the HOMO-LUMO energy differences. The determination of its optimized surface of the molecular electrostatic potential (MEP) was also carried out. This study was conducted to demonstrate both the electron-rich and electron-poor sites. [ABSTRACT FROM AUTHOR]

PALLADIUM catalysts, RING-opening reactions, ORGANIC synthesis, SILOXANES, ORGANIC chemistry, SILYL ethers, CHEMICAL reagents, and ETHYNYL benzene

Sequenced 3-methylene-silacyclobutane ring-opening with allylation reactions.[9] Ishida and colleagues have reported the ring-opening reaction of siletanes with carbon dioxide.[55] Development of this reaction began with the observation of an unexpected I cis i -to I trans i isomerization of 1,1,3-trimethyl-2-phenylsiletane in DMF-d7 (Scheme 21). Additionally, whereas the reaction of the cyclohexanone derived phenylsilacyclobutane enol ether with less reactive aldehydes such as isobutyraldehyde was found to be impractically slow ( I ca i . one-tenth the rate of reaction with benzaldehyde), the silacyclobutane silyl ketene acetal reacted efficiently with isobutyraldehyde (0.2 M, benzene, 1 day, 60 °C, 80%) and acetone (excess, benzene, 3 days, 65 °C, 85%). Effect of spectator substituent (R) on aldol reactions silacyclobutyl O-O-ketene acetals.[15] Coupled with a chiral Lewis acid, aldol reactions of enoxysilacyclobutanes can be made enantioselective (by contrast, attempted chiral Lewis base-catalyzed aldol reactions using a monochloro silacyclobutane I O,O i -ketene acetal were unsuccessful[67]). The authors report that each of these silacyclobutane-accelerated aldol reactions can be catalyzed by potassium I tert i -butoxide, suggesting these reactions are mechanistically distinct from the non-catalyzed process (i.e. nucleophilic activation of silicon by I tert i -butoxide versus siletane carbonyl coordination). [Extracted from the article]

ACID catalysts, PYRAZOLES, ETHYL acetoacetate, ORGANIC chemistry, and MELTING points

.5Trace ht 1 SP a sp Reaction conditions: B 1 b (1 mmol), B 2 b (1 mmol), B 3a b (1 mmol), B 4 b (1 mmol), catalyst (15 mol%), in solvent (10 mL). 3 ht 3 SP a sp Reaction conditions: B 1 b (1 mmol), B 2 b (1 mmol), B 3a b (1 mmol), B 4 b (1 mmol) and (DL)-mandelic acid in water (10 mL) for 1.5 h. 4 SP b sp Isolated yields. The success of green chemistry in the drug discovery process is considerably dependent on new advances in methodology for heterocyclic multi-component reactions (MCRs) and on new developments in environmentally benign MCR procedures.[[1], [3]] Pyrazoles are a vital class of compounds in drug development, as they comprise the core structures of numerous blockbuster drugs such as celecoxib, viagra, and pyrazofurine, among others.[[4], [6]] Compounds with the dihydropyrano[2,3-C]pyrazole moiety[7] have anticancer,[8] analgesic,[9] anti-inflammatory,[10] antimicrobial[11] and molluscicidal activities.[12] These molecules are also used as potential inhibitors of human Chk1 kinase.[13] Thus, the formation of dihydropyrano[2, 3-C]pyrazoles is an important and useful task in preparative organic chemistry. [Extracted from the article]

DERIVATIVES (Mathematics), BIOACTIVE compounds, ORGANIC chemistry, MELTING points, and INDOLINE

Initially, in order to find the optimized reaction conditions, we chose the three-component reaction of B 3 b , isatin ( B 4a b ), and malononitrile ( B 5 b ) as a model (Table 1). In summary, a catalyst-free and facile procedure has been described for the synthesis of novel spiro heterocycles B 6 b I via i a one-pot three-component condensation reaction among dione B 3 b , isatins and malononitrile in ethanol/water. After completion of the reaction, the reaction mixture was cooled to room temperature and thereafter the precipitated product was separated from the reaction mixture by simple filtration, then washed three times with EtOH (20 mL). This was accomplished I via i a one-pot three-component condensation reaction among B 3 b , isatin derivatives ( B 4a-m b ), and malononitrile ( B 5 b ). [Extracted from the article]

CARBONIC anhydrase inhibitors, SULFONAMIDES, PYRIDINE, ORGANIC chemistry, BURKHOLDERIA pseudomallei, and CELLULOSE acetate

Carbonic anhydrases (CAs, EC 4.2.1.1) catalyze the essential reaction of CO2 hydration in all living organisms, being actively involved in the regulation of a plethora of patho-/physiological conditions. A series of chromene-based sulfonamides were synthesized and tested as possible CA inhibitors. On the other hand, in microorganisms, the β- and γ- classes are expressed in addition to the α- class, showing substantial structural differences to the human isoforms. In this scenario, not only human but also bacterial CAs are of particular interest as new antibacterial agents with an alternative mechanism of action for fighting the emerging problem of extensive drug resistance afflicting most countries worldwide. Pyrazolo[4,3-c]pyridine sulfonamides were synthesized using methods of organic chemistry. Their inhibitory activity, assessed against the cytosolic human isoforms hCA I and hCA II, the transmembrane hCA IX and XII, and β- and γ-CAs from three different bacterial strains, was evaluated by a stopped-flow CO2 hydrase assay. Several of the investigated derivatives showed interesting inhibition activity towards the cytosolic associate isoforms hCA I and hCA II, as well as the 3β- and 3γ-CAs. Furthermore, computational procedures were used to investigate the binding mode of this class of compounds within the active site of hCA IX. Four compounds (1f, 1g, 1h and 1k) were more potent than AAZ against hCA I. Furthermore, compound 1f also showed better activity than AAZ against the hCA II isoform. Moreover, ten compounds out of eleven appeared to be very potent against the γ-CA from E.coli, with a Ki much lower than that of the reference drug. Most of the compounds showed better activity than AAZ against hCA I as well as the γ-CA from E.coli and the β-CA from Burkholderia pseudomallei (BpsCAβ). Compounds 1f and 1k showed a good selectivity index against hCA I and hCA XII, while 1b was selective against all 3β-CA isoforms from E.coli, BpsCA, and VhCA and all 3γ-CA isoforms from E.coli, BpsCA and PgiCA. [ABSTRACT FROM AUTHOR]

DISTILLATION, BIOMETRY, ERROR rates, VANILLA, and ORGANIC chemistry

This work addresses the challenge of building an accurate and generalizable periocular recognition model with a small number of learnable parameters. Deeper (larger) models are typically more capable of learning complex information. For this reason, knowledge distillation (kd) was previously proposed to carry this knowledge from a large model (teacher) into a small model (student). Conventional KD optimizes the student output to be similar to the teacher output (commonly classification output). In biometrics, comparison (verification) and storage operations are conducted on biometric templates, extracted from pre-classification layers. In this work, we propose a novel template-driven KD approach that optimizes the distillation process so that the student model learns to produce templates similar to those produced by the teacher model. We demonstrate our approach on intra- and cross-device periocular verification. Our results demonstrate the superiority of our proposed approach over a network trained without KD and networks trained with conventional (vanilla) KD. For example, the targeted small model achieved an equal error rate (EER) value of 22.2% on cross-device verification without KD. The same model achieved an EER of 21.9% with the conventional KD, and only 14.7% EER when using our proposed template-driven KD. [ABSTRACT FROM AUTHOR]

DIAZOALKANES, VISIBLE spectra, PHYSICAL organic chemistry, ORGANIC chemistry, CARBENE synthesis, and ORGANIC synthesis

Photochemistry has recently attracted the interest of synthetic chemists to conduct photolysis reactions of diazoalkanes. In this feature article, we provide a concise overview on this field, starting with discoveries in physical organic chemistry and then discuss examples in organic synthesis of singlet carbene intermediates, ranging from classic reactivity towards advances in cascade reactions and unusual protonation reactions under photochemical conditions. We then commence with a discussion on the electronic control of singlet and triplet carbene intermediates and last discuss the advances that have been made with regards to the reaction of weakly colored diazoalkanes in dye-sensitized reactions to access radical or triplet carbene intermediates. [ABSTRACT FROM AUTHOR]

HETEROGENEOUS catalysts, HETEROCYCLIC compounds synthesis, ORGANIC chemistry, CHEMICAL stability, CATALYST synthesis, and HETEROCYCLIC compounds

The field of reusable nano‐catalysts has grown rapidly over the last decade. Recently, transition metal catalysed organic reactions have attracted considerable interest from the pharmaceutical and organic chemistry fields. Synthetic procedures based on such heterogeneous nanocatalysts are easier, less expensive, non‐toxic, and eco‐friendly, producing only the most desirable products in higher yields and allowing for easy catalyst separation. Heterogeneous nano‐catalysts were highly preferred over homogeneous catalysts for the synthesis of heterocyclic compounds due to their effective separation processes for both products and catalysts. According to recent studies, nanoparticles (NPs) are commonly used as a heterogeneous catalyst in the production of heterocyclic compounds. Heterogeneous catalysts are widely used in a variety of organic reactions due to their high surface‐to‐volume ratio. Most importantly, after the reaction is complete, easy magnetic separation of the catalyst minimises the requirement for catalyst filtration. Additionally, magnetic NPs, particularly supported magnetic nanocatalysts, have garnered considerable interest in both academic and industrial research due to their effectiveness as alternatives to traditional materials, their ease of separation via an external magnet, and their high degree of chemical stability in a variety of organic and inorganic solvents. To reach its depth, this review is focused on the most recent examples, their preparation, synthetic strategies and recycling studies of highly excited catalytic systems used for the synthesis of heterocyclic compounds. [ABSTRACT FROM AUTHOR]

METAL-organic frameworks, CORROSION & anti-corrosives, INORGANIC chemistry, ORGANIC chemistry, METAL ions, and SURFACE area

[Display omitted] • The fundamental understanding of MOF materials for corrosion protection is provided. • Fabrication approaches of MOF-based anticorrosion materials are discussed. • The anticorrosion applications and protection mechanisms of MOFs are summarized. • Challenges and outlooks of MOFs to meet the needs of increasing corrosion protection demand are proposed. Metal-organic frameworks (MOFs), a subclass of hybrid-type crystalline materials that consist of metal ions (or clusters) and organic ligands, has received remarkable attention in both inorganic and organic chemistry fields in recent decades. Benefiting from their significant features such as large specific surface area, adjustable structure and function, regular pore arrangement and abundant active sites, MOFs exhibit great application prospects as anticorrosion materials. Herein, this review focuses on the latest research progress of MOF-based corrosion protection materials and reviews their anticorrosion performance, including the commonly concerned fabrication approaches of MOFs for corrosion protection with their respective advantages and shortcomings, the different anticorrosion applications, and the presented challenges that need to be conquered in practical applications. Meanwhile, we detailedly introduce the corrosion protection mechanisms of MOFs when serve as inhibitors, nano-fillers, nano-containers, and surficial protecting coatings. At the end of this review, the future outlooks of MOFs for corrosion protection is provided, we hope this review will illuminate the achievement of high performed anticorrosion MOFs and offer new ideas for the development of MOF-based materials for future corrosion protection application. [ABSTRACT FROM AUTHOR]

ANTIBACTERIAL agents, MESQUITE, GALLIC acid, TROPICAL dry forests, ETHYL acetate, SKIN infections, and TREE growth

Prosopis africana (G. &Perr.) Taub (Mimosaceae) is a large tree native to dry tropical Africa and characteristic of dry leguminous forests. Different parts of this plant are used to treat wounds, skin infection, and to fight against cancer. Literature review indicated various pharmacological properties. Despite these medicinal properties, the chemical composition studies remain limited. This study aims to isolate and characterize secondary metabolites from P. africana leaves and evaluate their antibacterial and antioxidant properties. Air-dried powdered leaves of P. africana were macerated in methanol at room temperature and partitioned with ethyl acetate. The EtOAc extract was subjected successively to flash and column chromatographies in order to isolate compounds. The structure of the isolates was determined with help of spectroscopic data including 1D and 2D NMR experiments and comparison with literature data. The antibacterial activities were evaluated via determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The antioxidant activities were evaluated via gallic acid equivalent antioxidant capacity (GEAC) and diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assays. The chemical investigation of the EtOAc extract led to the isolation of seven compounds: (2E, 6E) farnesylamine (1), myricetin-3-O-rhamnoside (2), bis(2-ethylhexyl) benzene-1,2-dicarboxylate (3), lupeol (4), ß-sitosterol (5), stigmasterol glycoside (6), and a mixture of bis(2-ethylhexyl) benzene-1,2-dicarboxylate (3) and bis(2-ethylhexyl) benzene-1,4-dicarboxylate (7) in ratio 1 : 2. Compound 1 is described here for the first time as a natural product with complete 1H and 13C assignments. Compounds 3 and 7 were identified as artefacts from dichloromethane. Sesquiterpene amine (1) is reported in Prosopis genus for the first time. Antibacterial and antioxidant activities of isolated compounds were investigated. Among the tested samples, the EtOAc extract and compound 2 exhibited the highest antioxidant (EC50 = 5.67–77.56 μg/mL; GEAC = 36.58–89.28 μg/mL) and antibacterial (MIC = 8–64 μg/mL) activities against gram-negative and gram-positive bacteria. The EtOAc extract and compound 2 from P. africana exhibited antibacterial activity through bacteriolytic effects and reduction of the antioxidant defenses in the bacterial cells. Furthermore, the chemotaxonomic significance of isolated compounds was discussed. The antibacterial and antioxidant activities of ethyl acetate extract and compound 2 can justify the traditional uses of P. africana leaves for the treatment of diseases related to bacterial infections. The presence of compounds 1, 2, and 4 in this plant should also be considered as valuable chemotaxonomic features. [ABSTRACT FROM AUTHOR]

EXCHANGE reactions, ALKYL group, ABILITY grouping (Education), LEWIS bases, ORGANIC chemistry, SUBSTITUTION reactions, and NUCLEOPHILIC substitution reactions

The carbon–fluorine (C–F) bond is one of the strongest bonds in organic chemistry and generally inert toward nucleophilic substitution reactions. To overcome the relative inertness of the C–F bond, this work focused on the ability of simple lithium salts (Lewis acid) to activate alkyl fluorides (Lewis base) leading to F/I exchange in high yields and selectivity for displacement of fluoride versus chloride and bromide. The exchange of fluorine for iodine was effective on both activated and neutral alkyl fluorides leading to yields as high as 99%. [Display omitted] The carbon–fluorine (C–F) bond is one of the strongest bonds in organic chemistry and generally inert toward nucleophilic substitution reactions. To overcome the relative inertness of the C–F bond, this work focused on the ability of simple lithium salts (Lewis acid) to activate alkyl fluorides (Lewis base) leading to F/I exchange in high yields and selectivity for displacement of fluoride versus chloride and bromide. The exchange of fluorine for iodine was effective on both activated and neutral alkyl fluorides leading to yields as high as 99%. [ABSTRACT FROM AUTHOR]

ARTIFICIAL photosynthesis, COMMUNICATIVE competence, SUPRAMOLECULAR chemistry, ORGANIC chemistry, CYCLODEXTRIN derivatives, and EXCIMERS

" I The natural talent I would like to be gifted with is the communication ability to make a good relationship with any person in the world ... Key experiences in my education / career were the extensive discussions with my respected mentors ..." i Find out more about Hajime Shigemitsu in his Introducing ... Profile. The obstacle was overcome by cooperation of Prof. Mori and Prof. Nagata who are experts in theoretical calculation, and the plausible conformer showing bright CPL could be determined. Position: Assistant Professor, Department of Applied Chemistry, Osaka University (Japan) Homepage: https://researchmap.jp/hajime shigemitsu ORCID: orcid.org/0000-0002-3104-049X Education: 2003-2007 B.Eng, Osaka University (Japan) 2007-2009 M.Eng, Osaka University (Japan) 2010-2013 PhD with Mikiji Miyata, Osaka University (Japan) 2013-2017 Postdoc with Itaru Hamachi, Kyoto University (Japan) Research: Supramolecular chemistry, photochemistry, organic materials chemistry Hobbies: Movie, drama, sauna B The biggest challenge facing my generation of scientists is b to develop chemistry for a sustainable society. [Extracted from the article]

ARTIFICIAL photosynthesis, COMMUNICATIVE competence, SUPRAMOLECULAR chemistry, ORGANIC chemistry, CYCLODEXTRIN derivatives, and EXCIMERS

The obstacle was overcome by cooperation of Prof. Mori and Prof. Nagata who are experts in theoretical calculation, and the plausible conformer showing bright CPL could be determined. " I The natural talent I would like to be gifted with is the communication ability to make a good relationship with any person in the world ... Key experiences in my education / career were the extensive discussions with my respected mentors ..." i Find out more about Hajime Shigemitsu in his Introducing ... Profile. Position: Assistant Professor, Department of Applied Chemistry, Osaka University (Japan) Homepage: https://researchmap.jp/hajime shigemitsu ORCID: orcid.org/0000-0002-3104-049X Education: 2003-2007 B.Eng, Osaka University (Japan) 2007-2009 M.Eng, Osaka University (Japan) 2010-2013 PhD with Mikiji Miyata, Osaka University (Japan) 2013-2017 Postdoc with Itaru Hamachi, Kyoto University (Japan) Research: Supramolecular chemistry, photochemistry, organic materials chemistry Hobbies: Movie, drama, sauna B The biggest challenge facing my generation of scientists is b to develop chemistry for a sustainable society. [Extracted from the article]

IRON catalysts, MAGNIFYING glasses, NITROGEN cycle, METAL catalysts, ROLE models, and ORGANIC chemistry

To our delight, the deoxygenation of N SB 2 sb O using the iron silanone complex as a catalyst and pinacolborane (HBpin) as a sacrificial reagent proceeds smoothly to form N SB 2 sb , H SB 2 sb , and (pinB) SB 2 sb O. The deoxygenation of the polarized Si-O bond would regenerate the iron silylene complex, thus providing an attractive catalytic strategy for the degradation of N SB 2 sb O. The actual question was to find a suitable oxygen acceptor. " I To improve my work-life balance I usually cook dinner for my family on the weekend ... My first experiment was setting my father's martial arts book on fire with a magnifying glass ... i " Find out more about Zhenbo Mo in his Introducing ... Profile. [Extracted from the article]

IRON catalysts, MAGNIFYING glasses, NITROGEN cycle, METAL catalysts, ROLE models, and ORGANIC chemistry

The deoxygenation of the polarized Si-O bond would regenerate the iron silylene complex, thus providing an attractive catalytic strategy for the degradation of N SB 2 sb O. The actual question was to find a suitable oxygen acceptor. To our delight, the deoxygenation of N SB 2 sb O using the iron silanone complex as a catalyst and pinacolborane (HBpin) as a sacrificial reagent proceeds smoothly to form N SB 2 sb , H SB 2 sb , and (pinB) SB 2 sb O. " I To improve my work-life balance I usually cook dinner for my family on the weekend ... My first experiment was setting my father's martial arts book on fire with a magnifying glass ... i " Find out more about Zhenbo Mo in his Introducing ... Profile. [Extracted from the article]

CHEMICAL amplification, NANOWIRES, PHOTOCATALYSIS, ELECTROCHEMISTRY, CATALYSIS, and ORGANIC chemistry

• Nanowires revealed appreciable catalytic performance in various reaction systems. • They successfully catalyze organic transformations such as coupling or reduction. • Their utility also extends to the areas of electrochemistry and photochemistry. [Display omitted] The ever-growing need for sophisticated chemical compounds drives progress in the field of catalysis. It is essential to devise new inexpensive catalytic systems to reduce reaction time, increase the yield, and put a smaller burden on the environment. The discovery of nanomaterials has breathed fresh air into this area. Extraordinary surface-to-volume ratio and various quantum effects made these materials a promising alternative to the traditional catalysts. Particularly notable results come from implementing metal species arranged in 1D, which are referred to as nanowires (NWs). In this review, we illustrate their potential to catalyze various chemical transformations in organic chemistry. We demonstrate how NWs facilitate processes such as coupling and reduction. Furthermore, we show how these species can be used in electrochemistry and photo-catalysis. Finally, having described the advances in these areas, we envision the next steps which should be taken to bring this concept to the phase of commercial implementation. [ABSTRACT FROM AUTHOR]

ANTIVIRAL agent synthesis, ANTIVIRAL agents, DIELS-Alder reaction, ORGANIC chemistry, ALDER, and ORGANIC synthesis

The Diels–Alder reaction (DAR) is one of the most effective and reliable strategies for the construction of six-membered carbocyclic and heterocyclic rings, and it is widely used in the synthesis of organic molecules and drugs. Due to the high regio- and stereo-selectivity and its versatility, DARs have represented a powerful tool for organic chemistry for many years. In addition, the asymmetric DAR has become a fundamental synthetic approach in the preparation of optically active six-membered rings and natural compounds. The COVID-19-related pandemic requires continuous research; DAR represents an useful method to obtain optically active intermediates for the synthesis of antiviral agents under different catalytic conditions. We would like to highlight an intriguing synthetic procedure applied to the development of novel synthetic protocols that are potentially useful against a large panel of viruses and other unmet diseases. [ABSTRACT FROM AUTHOR]

ALIPHATIC alcohols, ALCOHOL oxidation, ORGANIC chemistry, CHEMICAL reactions, PALLADIUM, and METAL catalysts

Extremely high electrophilic metal complexes, composed by a metal cation and very electron poor σ‐donor ancillary ligands, are expected to be privileged catalysts for oxidation reactions in organic chemistry. However, their low lifetime prevents any use in catalysis. Here we show the synthesis of fluorinated pyridine‐Pd2+ coordinate cages within the channels of an anionic tridimensional metal‐organic framework (MOF), and their use as efficient metal catalysts for the aerobic oxidation of aliphatic alcohols to carboxylic acids without any additive. Mechanistic studies strongly support that the MOF‐stabilized coordination cage with perfluorinated ligands unleashes the full electrophilic potential of Pd2+ to dehydrogenate primary alcohols, without any base, and also to activate O2 for the radical oxidation to the aldehyde intermediate. This study opens the door to design catalytic perfluorinated complexes for challenging organic transformations, where an extremely high electrophilic metal site is required. [ABSTRACT FROM AUTHOR]

LYOTROPIC liquid crystals, MOLECULAR shapes, NUCLEAR magnetic resonance spectroscopy, ORGANIC chemistry, NUCLEAR magnetic resonance, MOLECULAR spectroscopy, STEREOCHEMISTRY, and ENANTIOMERS

The study of enantiodiscriminations in relation to various facets of enantiomorphism (chirality/prochirality) and/or molecular symmetry is an exciting area of modern organic chemistry and an ongoing challenge for nuclear magnetic resonance (NMR) spectroscopists who have developed many useful analytical approaches to solve stereochemical problems. Among them, the anisotropic NMR using chiral aligning solvents has provided a set of new and original tools by making accessible all intramolecular, order‐dependent NMR interactions (anisotropic interactions), such as residual chemical shift anisotropy (RCSA), residual dipolar coupling (RDC), and residual quadrupolar coupling (RQC) for spin I > 1/2, while preserving high spectral resolution. The force of NMR in enantiopure, oriented solvents lies on its ability to orient differently in average on the NMR timescale enantiomers of chiral molecules and enantiotopic elements of prochiral ones, leading distinct NMR spectra or signals to be detected. In this compendium mainly written for all chemists playing with (pro)chirality, we overview various key aspects of NMR in weakly aligning chiral solvents as the lyotropic liquid crystals (LLCs), in particular those developed in France to study (pro)chiral compounds in relation with chemists needs: study of enantiopurity of mixture, stereochemistry, natural isotopic fractionation, as well as molecular conformation and configuration. Key representative examples covering the diversity of enantiomorphism concept, and the main and most recent applications illustrating the analytical potential of this NMR in polypeptide‐based chiral liquid crystals (CLCs) are examined. The latest analytical strategy developed to determine in‐solution conformational distribution of flexibles solutes using NMR in polypeptide‐based aligned solvents is also proposed. [ABSTRACT FROM AUTHOR]

ORGANIC synthesis, TRANSITION metals, METALLACYCLES, METAL activation, and ORGANIC chemistry

C−H Activation by transition metals has revolutionized the field of modern synthetic organic chemistry thereby enabling efficient and atom‐economical construction of complex organic frameworks in reduced number of steps. Various ways are being explored in order to maximize efficiency of the approach and construct previously unknown molecules. The major challenge in this aspect is the ubiquitous presence of C−H bond in an organic molecule that demands sophistication to achieve site‐selective functionalization. Directing group approach provided the most viable solution which operates through formation of a thermodynamically preferred metallacycle. Although, five and six membered metallacycles are known to be thermodynamically most favorable, there exists ingenious methodologies that operates through a four‐membered metallacycle in order to achieve site‐selectivity. In this review article, we summarize the C−H activation reactions evidenced to proceed via four‐membered metallacycle intermediate to achieve synthetically relevant transformations. [ABSTRACT FROM AUTHOR]

ORGANIC chemistry, PHENOL, ORGANIC acids, CHEMICAL decomposition, and PHOSPHOTUNGSTIC acids

In this work, a HPW/ZSM‐5 catalyst was prepared by impregnating phosphotungstic acid (HPW) with carrier ZSM‐5 zeolite and characterized by XRD, SEM, N2 adsorption/desorption isotherm, NH3‐TPD, and FT‐IR techniques. The catalytic performance of HPW/ZSM‐5 was investigated by using the decomposition reaction of cyclohexylbenzene‐1‐hydroperoxide (CHBHP) to phenol and cyclohexanone. The conversion rate of CHBHP was up to 97.28%. In addition, the reusability test exhibited that the high durability HPW/ZSM‐5 as the conversion rate of CHBHP only decreased by 3.11% after five runs. The kinetic study of the decomposition reaction indicated it was a primary reaction. The apparent activation energy of the decomposition reaction was 102.39 kJ·mol–1 in the temperature range of 45–60℃. All results indicate that the HPW/ZSM‐5 catalyst has good performance and promising applications in acid catalyzed organic chemistry. [ABSTRACT FROM AUTHOR]

HEPATITIS B virus, DNA replication, DNA viruses, HEPATITIS B, VIRAL replication, VIRAL mutation, and VIRAL hepatitis

Hepatitis B virus infection (HBV) is one of the most common causes of hepatitis, and may lead to cirrhosis or hepatocellular carcinoma. According to the World Health Organization (WHO), approximately 296 million people worldwide are carriers of the hepatitis B virus. Various nucleos(t)ide analogs, which specifically suppress viral replication, are the main treatment agents for HBV infection. However, the development of drug-resistant HBV strains due to viral genomic mutations in genes encoding the polymerase protein is a major obstacle to HBV treatment. In addition, adverse effects can occur in patients treated with nucleos(t)ide analogs. Thus, alternative anti-HBV drugs of plant origin are being investigated as they exhibit excellent safety profiles and have few or no side effects. In this study, phytomedicines/phytochemicals exerting significant inhibitory effects on HBV by interfering with its replication were reviewed based on different compound groups. In addition, the chemical structures of these compounds were developed. This will facilitate their commercial synthesis and further investigation of the molecular mechanisms underlying their effects. The limitations of compounds previously screened for their anti-HBV effect, as well as future approaches to anti-HBV research, have also been discussed. [ABSTRACT FROM AUTHOR]

ISOCYANIDES, ORGANIC chemistry, HETEROCYCLIC compounds, IMIDAZOPYRIDINES, SMALL molecules, and ORGANIC synthesis

A one‐pot methodology is developed for the direct conversion of N‐formylamine, 2‐amino pyridine, and aldehyde into 2,3‐substituted imidazo[1,2‐a]pyridine heterocycles using I2‐PPh3‐Et3N reagent system under microwave irradiation. During the reaction, I2‐PPh3‐Et3N converts N‐formylamine into isocyanide, which in the presence of in‐situ generated hydrogen iodide (HI) undergoes Groebke‐Balckburn‐Bienaymé (GBB) multicomponent reaction with aldehyde and 2‐aminopyridine. The in‐situ generated HI eliminates the need for an external catalyst for the GBB reaction. The developed process incorporates the use of readily accessible and cheap reagents and also avoid a separate step for the synthesis of isocyanides having disagreeable odor. Fourteen different GBB based heterocycles have been synthesized to demonstrate the feasibility of the optimized protocol. The preparation of N‐formylamines utilized in the synthesis is also elaborated and the overall process was optimized to be suitable for a typical undergraduate organic laboratory experiment. One of the final products was characterized using FT‐IR, 1H NMR, 13C NMR, DEPT, COSY, HSQC, HRMS, and single‐crystal X‐ray diffraction. Overall, the experiment will be useful in the organic chemistry curriculum to teach about multicomponent reactions, the importance of isocyanides in organic synthesis, formylation of amines, application of microwave irradiation in organic synthesis, and structural elucidation of small organic molecules. [ABSTRACT FROM AUTHOR]

IONIC liquids, ORGANIC synthesis, IONIC structure, ORGANIC chemistry, CHEMICAL reactions, SOLVENTS, and AQUEOUS solutions

[Display omitted] • A review on surface-active ionic liquids in aqueous media is presented. • The general structure and aggregation behavior of surface-active ionic liquids is discussed. • Common characterization techniques of the formed micelles are described. • Current applications of surface-active ionic liquids in water are highlighted. The combination of water and surface-active ionic liquids provides a unique reaction medium, facilitating aggregation and micellization of the ionic liquid to allow for chemical reactions in bulk water. With a growing focus on sustainable technologies, ionic liquids have emerged as tunable solvents for multiple applications but are often too viscous or expensive for use as bulk solvent. As a result, there has been a tremendous increase in interest in the behavior of ionic liquids in the presence of water. It has already been shown that certain ionic liquids act as surfactants in aqueous solutions, enabling the combination of both solvents to afford solvent systems with unique properties. Ultimately, surface-active ionic liquids in water give rise to distinct chemistry of their own compared to traditional molecular solvents, and thus their use is rapidly growing. In this review, the general structure of surface-active ionic liquids and the key features that allow aggregation in water to give micellar structures is discussed. Furthermore, characterization techniques of the formed micelles are presented, discussing aggregation and possible methods of studying micellization behavior. Finally, current applications of surface-active ionic liquids across all fields of chemistry, from traditional organic chemistry to nanoparticle synthesis are presented. [ABSTRACT FROM AUTHOR]

OXIDATION-reduction reaction, ORGANIC chemistry, MICELLAR catalysis, CHARGE exchange, MICELLAR solutions, and METAL ions

[Display omitted] • Redox active centers, Cu(III) and Fe(III) emerged as good one electron accepting agents. • Aqueous micellar solution drives the organic transformations efficiently. • Considering environmental health use of surfactant is crucial rather than that of organic solvents. • Cu(III)periodate complex directed electron transfer oxidations illustrated comprehensively. • Iron(III)polypyridyl complex administered electron transfer oxidations exemplified in detail. Organic transformations associated with metal mediated electron transfer processes are really worthy of remarkable considering the biological importance of redox active metal ions, such as Cu(III) and Fe(III). Electron transfer reactions directed by those metal ions, offer numerous oxidative transformations, have significant interest to the researchers in order to correlate with biological systems as well as to understand the kinetics and mechanistic pathways of those studied reactions. This review aims to recapitulate the considerable development of Cu(III) and Fe(III) mediated redox transformations. As biological systems are associated with water therefore thorough exploration on the electron transfer reactions by two redox couples in aqueous medium has been getting much importance over simple redox chemistry in organic media. So, by replacing organic solvent with environmentally benign water media, aqueous surfactant solution appeared as the best substitute. It is known to all that 'micellar catalysis' is a legendary term recognized for its practical application in several organic transformations that are really difficult to perform in water without exploiting surfactant. This review emphasizes also the significance of surfactant-micelle media on the Cu(III) and Fe(III) metal ions directed oxidative transformations along with a focus on the exclusive catalytic track and significant contributory interaction accounted for in the course of rate enhancement. Despite the detailing about the current progress and developing prospects of micellar media on such organic transformations this review would be helpful to the researchers working in this field to generate some thoughtful ideas. [ABSTRACT FROM AUTHOR]

HECK reaction, ORGANIC chemistry, ENVIRONMENTAL reporting, OXIDATIVE coupling, PALLADIUM catalysts, NATURAL products, and RING formation (Chemistry)

• The first review on Rh-Catalysed Heck type reactions. • Environmentally benign couplings with reports in green solvents. • Wide applicability in natural product synthesis. • Oxidative, decyanative, desulfitative and decarbonylative heck reactions are included. Heck coupling has emerged as a powerful tool for C C bond construction in organic chemistry. Traditionally, Heck reactions were catalysed by Pd, however sufficient research is done on rhodium-catalysed Heck type reactions due to its high efficiency. A wide range of Heck type coupling including oxidative, decyanative, desulfitative, decarbonylative Heck reaction, and even Heck type cyclizations have been described so far. Herein, we summarize the first review giving an overview of rhodium-catalysed Heck type reactions covering literature until 2021. [Display omitted] [ABSTRACT FROM AUTHOR]

During the COVID-19 pandemic, various drug candidates have been developed, molnupiravir (MK-4482 and EIDD-2801), which is a new orally anti-viral agent under development for the treatment of COVID-19, is under study in the final stage of the clinical trial. Molnupiravir enhances the replication of viral RNA mutations in animals and humans. Due to the high demand for the synthesis of this drug, it was essential to develop an efficient and suitable synthetic pathway from raw material. In this study, molecular docking analysis on molnupiravir is examined also, the mechanism of action (MOA) and the recent synthetic pathway is reported. This review will be helpful to different disciplines such as medicinal chemistry, organic chemistry, biochemistry, and pharmacology. [ABSTRACT FROM AUTHOR]

MOLECULAR docking, ANTI-infective agents, ANTIBACTERIAL agents, ANTIFUNGAL agents, BIFONAZOLE, ORGANIC chemistry, and MUPIROCIN

Background: Infectious diseases represent a significant global strain on public health security and impact on socio-economic stability all over the world. The increasing resistance to the current antimicrobial treatment has resulted in the crucial need for the discovery and development of novel entities for the infectious treatment with different modes of action that could target both sensitive and resistant strains. Methods: Compounds were synthesized using the classical organic chemistry methods. Prediction of biological activity spectra was carried out using PASS and PASS-based web applications. Pharmacophore modeling in LigandScout software was used for quantitative modeling of the antibacterial activity. Antimicrobial activity was evaluated using the microdilution method. AutoDock 4.2® software was used to elucidate probable bacterial and fungal molecular targets of the studied compounds. Results: All compounds exhibited better antibacterial potency than ampicillin against all bacteria tested. Three compounds were tested against resistant strains MRSA, P. aeruginosa and E. coli and were found to be more potent than MRSA than reference drugs. All compounds demonstrated a higher degree of antifungal activity than the reference drugs bifonazole (6–17-fold) and ketoconazole (13–52-fold). Three of the most active compounds could be considered for further development of the new, more potent antimicrobial agents. Conclusion: Compounds 5b (Z)-3-(3-hydroxyphenyl)-5-((1-methyl-1H-indol-3-yl)methylene)-2-thioxothiazolidin-4-one and 5g (Z)-3-[5-(1H-Indol-3-ylmethylene)-4-oxo-2-thioxo-thiazolidin-3-yl]-benzoic acid as well as 5h (Z)-3-(5-((5-methoxy-1H-indol-3-yl)methylene)-4-oxo-2-thioxothiazolidin-3-yl)benzoic acid can be considered as lead compounds for further development of more potent and safe antibacterial and antifungal agents. [ABSTRACT FROM AUTHOR]

LACTOBACILLUS fermentum, ENANTIOMERIC purity, ORGANIC chemistry, MATHEMATICAL optimization, ETHANOL, and ENZYMES

The biocatalytic asymmetric reduction of prochiral ketones is a significant transformation in organic chemistry as chiral carbinols are biologically active molecules and may be used as precursors of many drugs. In this study, the bioreduction of 1-(benzo [d] [1,3] dioxol-5-yl) ethanone for the production of enantiomerically pure (S)-1-(1,3-benzodioxal-5-yl) ethanol was investigated using freeze-dried whole-cell of Lactobacillus fermentum P1 and the reduction conditions was optimized with a D-optimal experimental design-based optimization methodology. This is the first study using this optimization methodology in a biocatalytic asymmetric reduction. Using D-optimal experimental design-based optimization, optimum reaction conditions were predicted as pH 6.20, temperature 30 °C, incubation time 30 h, and agitation speed 193 rpm. For these operating conditions, it was estimated that the product could be obtained with 94% enantiomeric excess (ee) and 95% conversion rate (cr). Besides, the actual ee and cr were found to be 99% tested under optimized reaction conditions. These findings demonstrated that L. fermentum P1 as an effective biocatalyst to obtain (S)-1-(1,3-benzodioxal-5-yl) ethanol and with the D-optimal experimental design-based optimization, this product could be obtained with the 99% ee and 99% cr. Finally, the proposed mathematical optimization technique showed the applicability of the obtained results for asymmetric reduction reactions. [ABSTRACT FROM AUTHOR]

LIGNOCELLULOSE, HEMICELLULOSE, ETHYLENE, ETHANOL as fuel, CHEMICAL processes, BIOMASS chemicals, ORGANIC chemistry, and INTERNAL combustion engine exhaust gas

4 Commercial status of bioethanol dehydration to bioethylene Ethylene from ethanol dehydration was first produced on the commercial scale in 1913 at Elektrochemische Werke GmbH in Bitterfeld, Germany ([133]). The catalyst activity and product selectivity depends on the kind of alcohol, kind of catalyst and process conditions, while the trend of alcohol dehydration observed in this research work was as follows: 2-propanol > l-propanol > ethanol, in accordance with the relative stabilities of the corresponding carbenium ions. Keywords: bioethanol; bioethylene; catalyst; dehydration; techno-economic feasibility EN bioethanol bioethylene catalyst dehydration techno-economic feasibility 185 207 23 02/07/22 20220201 NES 220201 1 Introduction The rise in oil prices, environmental issues due to toxic emissions caused by the combustion of fossil fuel and depletion of fossil fuel resources have a demand for an alternative pathway to produce green energy from waste streams ([69]; [74]; [101]; [189]). Another possibility is that three processes can co-occur such as ethanol dehydration to ethylene, ethanol transformation to ether or ether dehydration to ethylene as shown in Figure 7 ([30]; [114]; [161]). 5 Pathways and mechanisms of bioethanol dehydration to bioethylene During the middle of the previous century, much work has been conducted by different researchers to study the reaction mechanism of ethanol conversion to ethylene by dehydration in the presence of various catalysts ([49]; [71]; [82]; [110]; [159]; [166]). [Extracted from the article]

RADICALS (Chemistry), ORGANIC chemistry, POLYMERIZATION, SYNCHROTRON radiation sources, SCANNING force microscopy, and MATERIALS science

ORGANIC chemistry

B The greatest scientific advance of the last decade was b the development of rapid genome sequencing tools and the many open-source web-based analyses tools, from which all fields of natural product chemistry have benefitted. " I My biggest motivation is to accomplish and create something that makes a difference ... My motto is that new findings always pave the way to new intriguing research questions, and that Mother Nature might have already invented it i ..." Find out more about Christine Beemelmanns in her Introducing ... Profile. B The biggest change in my scientific working environment in the past 10 years has been b to establish a research group in natural product chemistry B My group has fun by b playing table soccer. [Extracted from the article]

ORGANIC chemistry, PROFESSIONAL education, and CHEMISTS

Held June 24–25, 2021, the third annual Empowering Women in Organic Chemistry (EWOC) conference gathered organic chemists at all stages of the career pipeline for rich professional development opportunities and a showcase of recent scientific achievements. This Meeting Review outlines the program. [ABSTRACT FROM AUTHOR]