articles+ search results

Organic Chemistry, High energy, Organic chemist, Intellectual development, Spin chemistry, Physical organic chemistry, History of science, Photochemistry, Chemistry, Supramolecular chemistry, and Electronic spin

This Perspective presents a review and survey of the science and philosophy of my research career over the past five decades at Columbia as a physical organic chemist and photochemist. I explore the role of paradigms, structure, and geometric thinking in my own cognitive and intellectual development. The Perspective describes my investigations of high energy content molecules in electronically excited states and the development of electronic spin and supramolecular photochemistry chemistry. Current research dealing with the nuclear spin chemistry of H2 incarcerated in buckyballs is illustrated. In the second part of this Perspective, I recount a personal role of the philosophy and history of science and the scientific communities’ use of paradigms in their every day research and intellectual activities. Examples are given of the crucial role of geometry and structure in the rapid development of organic chemistry and physical organic chemistry over the past century.

Library and Information Sciences, Computer Science Applications, General Chemical Engineering, General Chemistry, Computational chemistry, Combinatorial Chemistry Techniques, Combinatorial chemistry, Medicinal chemistry, and Drug discovery

As part of a large medicinal chemistry program, we wish to develop novel selective estrogen receptor modulators (SERMs) as potential breast cancer treatments using a combination of experimental and computational approaches. However, one of the remaining difficulties nowadays is to fully integrate computational (i.e., virtual, theoretical) and medicinal (i.e., experimental, intuitive) chemistry to take advantage of the full potential of both. For this purpose, we have developed a Web-based platform, Forecaster, and a number of programs (e.g., Prepare, React, Select) with the aim of combining computational chemistry and medicinal chemistry expertise to facilitate drug discovery and development and more specifically to integrate synthesis into computer-aided drug design. In our quest for potent SERMs, this platform was used to build virtual combinatorial libraries, filter and extract a highly diverse library from the NCI database, and dock them to the estrogen receptor (ER), with all of these steps being ful...

Physical and Theoretical Chemistry, General Physics and Astronomy, General Chemistry, Chemical kinetics, Chemical reaction, Photochemistry, Standard enthalpy of formation, Chemical nomenclature, Atmospheric chemistry, Kinetic energy, Chemistry, Experimental data, and Quantum yield

This paper updates and extends part of the previous data base of critical evaluations of the kinetics and photochemistry of gas-phase chemical reactions of neutral species involved in atmospheric chemistry [J. Phys. Chem. Ref. Data 9, 295 (1980); 11, 327 (1982); 13, 1259 (1984); 18, 881 (1989); 21, 1125 (1992); 26, 521 (1997); 26, 1329 (1997)]. The present evaluation is limited to the organic family of atmospherically important reactions. The work has been carried out by the authors under the auspices of the IUPAC Subcommittee on Gas Phase Kinetic Data Evaluation for Atmospheric Chemistry. Data sheets have been prepared for 171 thermal and photochemical reactions, containing summaries of the available experimental data with notes giving details of the experimental procedures. For each thermal reaction, a preferred value of the rate coefficient at 298 K is given together with a temperature dependence where possible. The selection of the preferred value is discussed and estimates of the accuracies of the rate coefficients and temperature coefficients have been made for each reaction. For each photochemical reaction the data sheets list the preferred values of the photoabsorption cross sections and the quantum yields of the photochemical reactions together with comments on how they were selected. The data sheets are intended to provide the basic physical chemical data needed as input for calculations which model atmospheric chemistry. A table summarizing the preferred rate data is provided, together with an Appendix listing the available values of enthalpies of formation of the reactant and product species.

General Chemistry, Catalysis, Organic Chemistry, Dioxomolybdenum, N-heterocycles, Nitroaromatics, Photophysical properties, Reuse of waste, Química orgánica, Chemistry, Organic, Full Paper, Full Papers, Hot Paper, dioxomolybdenum, nitroaromatics, photophysical properties, and reuse of waste

A catalytic domino reduction–imine formation–intramolecular cyclization–oxidation for the general synthesis of a wide variety of biologically relevant N‐polyheterocycles, such as quinoxaline‐ and quinoline‐fused derivatives, and phenanthridines, is reported. A simple, easily available, and environmentally friendly dioxomolybdenum(VI) complex has proven to be a highly efficient and versatile catalyst for transforming a broad range of starting nitroarenes involving several redox processes. Not only is this a sustainable, step‐economical as well as air‐ and moisture‐tolerant method, but also it is worth highlighting that the waste byproduct generated in the first step of the sequence is recycled and incorporated in the final target molecule, improving the overall synthetic efficiency. Moreover, selected indoloquinoxalines have been photophysically characterized in cyclohexane and toluene with exceptional fluorescence quantum yields above 0.7 for the alkyl derivatives.
A catalytic domino reduction / imine formation / intramolecular cyclization / oxidation allows the synthesis of a wide variety of biologically relevant N‐polyheterocycles. The reported process employs an inexpensive and nontoxic dioxomolybdenum(VI) complex as catalyst, easily available nitroarenes as starting materials and different glycols as reducing agents with reuse of the waste reduction carbonyl byproduct, which is embodied into the final compounds.

Article, Sulfides, Alcohols, Column chromatography, Cyclization, Propargyls, Química orgánica, Chemistry, Organic, and Organic Chemistry

This work describes the 6-endo-dig cyclization of Saryl propargyl sulfides to afford 2H-thiochromenes. The substitution at the propargylic position plays a crucial role in allowing intramolecular silver-catalyzed alkyne hydroarylation and Niodosuccinimide-promoted iodoarylation. Additionally, a PTSAcatalyzed thiolation reaction of propargylic alcohols was developed to synthesize the required tertiary S-aryl propargyl ethers. The applicability of merging these two methods is demonstrated by synthesizing the retinoic acid receptor antagonist AGN194310.
Junta de Castilla y León and FEDER (BU291P18 and BU049P20) and Ministerio de Ciencia e Innovación and FEDER (CTQ2016-75023-C2-1-P) for financial support. The project leading to these results has received funding from “la Caixa” Foundation, under Agreement LCF/PR/PR18/51130007> (CAIXA-UBU001). N.V., F.M.-L., and S.S.-P. thank Junta de Castilla y León and FSE and FEDER for predoctoral (N.V. and F.M.-L.) and postdoctoral (S.S.-P.) contracts, respectively.

General Chemical Engineering, General Chemistry, Química orgánica, and Chemistry, Organic

Thioamide groups represent useful hydrogen-bonding motifs for the development of active transmembrane anion transporters. Using a 1,8-di(thioamido)carbazole scaffold the superior performance of thioamides compared with the parent amides has been demonstrated.
Polish National Science Centre for grant OPUS (2011/01/B/ST5/03900) and Consejer´ıa de Educaci´on de la Junta de Castilla y Le´on (project BU067P20)

Organic Chemistry, Physical and Theoretical Chemistry, Chemistry, Organic chemistry, Amorfrutin C, Science & Technology, Physical Sciences, Chemistry, Organic, Aromatization, Biomimetic synthesis, Cyclization, Ketenes, Natural products, 0304 Medicinal and Biomolecular Chemistry, and 0305 Organic Chemistry

Amorfrutin C, a C-5 prenyl amorfrutin, its allyl analog and an amorfrutin C-5 aldehyde have been synthesized using a biomimetic strategy from non-aromatic precursors. In this approach, a dioxinone derived β,δ-diketo ester underwent a decarboxylative Pd(0) catalyzed prenyl migration to give a β,δ-diketo dioxinone, which readily aromatized giving the amorfrutin core. The introduction of prenyl and allyl moieties at the C-5 position of the scaffold was accomplished using a Claisen rearrangement. Alternatively, iodination, lithium-iodine exchange and trapping with DMF gave the amorfrutin aldehyde and an amorfrutin alcohol when excess n-BuLi was used.