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ORGANIC chemistry and PETROLEUM

CHEMISTRY education in universities & colleges and ORGANIC chemistry

Discusses a modern approach to teaching organic chemistry. Organic chemistry courses must begin with structure. Suggests using nuclear magnetic resonance spectroscopy to introduce structure; Introduce students to symmetry axes and planes; Review valence of hydrogen and first-row elements; Give them the equation for calculating the number of sites of unsaturation from the molecular formula; Give students the results of 13C{1H} DEPT with details later; More.

POLYMER research and MASS spectrometry

Examines proposed partial least squares (PLS) multivariate statistical models for predicting concentration of hydrocarbon- and oxygen-containing functional groups for a calibration set of model homopolymers. Plasma-deposited films; Static secondary ion mass spectrometry (SIMS); PLS modeling; Preprocessing; Prediction of surface oxygen and hydrogen concentration.

SEDIMENTATION & deposition research, OCEAN bottom, and CARBONATE minerals

Discusses the mechanism underlying the relative deposition rates of organic carbon and calcite to the sea floor. Effect of total calcite concentration on the specific depth at which calcite dissolves; Control of atmospheric carbon dioxide by ocean carbonate chemistry; Organic carbon degradation in the sediments.

GUMS & resins, ALLERGIES, COLOPHONS, GLYCERYL ethers, PATIENTS, and NUCLEAR magnetic resonance

In the esterification of rosin with glycerol, the main compound formed, glyceryl triabietate, shows low allergenic activity. In this study, compounds formed in smaller amounts, when abietic add (main component in rosin) was esterified with glycerol, were identified as glyceryl-1-monoabietate (GMA), glyceryl-1,2-diabietate (GDA,1,2) and glycery-1,3-diabietate (GDA1,3), using nuclear magnetic resonance (NMR), infra-red (IR) and mass spectrometry (MS) analyses. According to animal experiments, OMA was a contact allergen. No cross-reactivity was seen to allergens in unmodified rosin. Some patients allergic to unmodified rosin reacted when tested with GMA. No reactions were seen to the 2 diabietates. Some patients also reacted to commercial glycerol-modified rosins. OMA together with unmodified abietic acid were identified in these rosin samples. The reactions seen in rosin-sensitive patients to commercial glycerol-esterified rosins probably derive from the unmodified material still present in the product, but could also be the result of OMA obtained from the glycerol derivatization. [ABSTRACT FROM AUTHOR]

RING formation (Chemistry) and TRANSITION metals

Reviews the theoretical and mechanical metal-assisted cycloaddition transition reactions in organic chemistry. Organic and organometallic reactions; Schematically simulated reactions; Metal-assisted transition.

INSECT sex attractants, GRACILLARIIDAE, TORTRICIDAE, YPONOMEUTIDAE, OECOPHORIDAE, PYRALIDAE, GELECHIIDAE, and ALCOHOLS (Chemical class)

Field screening tests of 21 saturated and monounsaturated straight chain C12 and C14 alcohols and their acetates as well as some binary mixtures in dosages of 1 and 0.2 mg/dispenser were carried out in Lithuanian in 1993 and 1994. New sex attractants were determined for males of five moth species of the family Gracillariidae ( E10-12:OH for Phyllonorycter sorbi, E10-12Ac for Ph. cydoniella and Ph. oxyacanthae, Z10-12:OAc for Ph. junoniella, and a mixture of Z10-14:OAc with E9-14:OAc in a 1:10 for Ph. sylvella), for four species of the family Tortricidae ( E10-14:OAc for Endothenia ericetana, Z10-14:OAc in a 10:1 mixture with E11-14:OAc for Eudemis pozphyrana, E11-14:OAc in a 10:1 mixture with E11-14:OH for Dichrorampha petiverella and Cochylis dubitana), for two species of Gelechiidae ( Z9-14:OAc in a mixture with either Z10-14:OAc in a ratio 1:1, E9-14:OAc in a ratio 1:10 or E10-14:OAc in a ratio 10:1 for Bryotropha galhanella, Z10-14:OAc and E9-14:OAc in a ratio 10:1 for B. mundella), as well as for one species of each of the families Yponomeutidae ( Z7-14:OAc for Paraswammerdamia lutarea) and Oecophoridae ( Z10-14:OAc and E9-14:OAc in a ratio 10:1 for Pseudatemelia josephinae). Preliminary composition of sex attractants was established for three moth species of the family Gracillariidae ( Z10-14:OAc in a 1:10 mixture with E9-14:OAc for Phyllonorycter heegerella, Ph. coryli and Ph. dubitella) and for one species of the family Gelechiidae ( Z9-14:OAc for Bryotropha terella). Inhibitors of the sex attractants were found for four leafminer species of the family Gracillariidae ( Z7-, Z9- and Z10-12:OAc for Phyllonorycter sorbi, Z10-, E10-12:OH and E10-14:OH for Ph. mespilella, E10-12:OH for Ph. cydoniella, Z10-12:OH and E10-14:OH for Ph. oxyacanthae), for three species of Tortricidae ( E9-, Z11- and E11-14:OAc for Endothenia ericetana, E11-14:OAc for Gypsonoma minutana, E10- and E11-14:OAc for Epagoge grotiana), and for one species from the family Pyralidae ( Z10-, E10- and E11-14:OAc for Pyrausta aurata). Data from male behaviour tests in tube olfactometers are presented for Phyllonorycter blancardella, Ph. sorbi, Ph. dubitella and Ph. strigulatella and active compounds revealed. [ABSTRACT FROM AUTHOR]

LEAFMINERS, INSECT sex attractants, and PHEROMONES

Dodecyl acetate (12:OAc) (E)-10-dodecenyl acetate (E10-12:OAc) and (E)-10-dodecenol (E10-12:OH) in the ratio 8 : 80 : 12 were collected by solid phase micro-extraction of the volatiles emitted by virgin signalling females of the spotted tentiform leafminer moth, Phyllonorycter blancardella. The same compounds in the ratio 8 : 79 : 13 were extracted from the sex pheromone glands of virgin signalling females of the same species. The chemical structures of the compounds were identified by gas chromatography and mass spectrometry. Trapping results obtained from field tests using synthetic components of the sex pheromone demonstrated that only one component, E10–12:OAc, was essential for the attraction of conspecific males and should be considered as a sex pheromone. [ABSTRACT FROM AUTHOR]

THERMAL analysis, THERMODYNAMICS, INORGANIC chemistry, ORGANIC compounds, and POLYMERS

Summarizes developments and applications in thermal analysis that appeared in Chemical Abstracts from October 1997 to October 1999. Instrumentation; Thermodynamic measurements; Kinetic considerations; Inorganic chemistry; Organic and polymeric materials; Biochemical and natural products; Pharmaceutical applications; Minerals.

OLFACTORY nerve, TOBACCO, MOTH flies, SMELL, CHROMATOGRAPHIC analysis, and ELECTROPHYSIOLOGY

An important question in olfaction is for which odorants receptor neurones have evolved. In the present study, olfactory receptor neurones on the antennae of the tobacco budworm moth Heliothis virescens were screened for sensitivity to naturally occurring plant-produced volatiles by the use of gas chromatography linked to electrophysiology. Volatiles of host as well as non-host plants collected by headspace techniques were used for stimulating the neurones, sequentially via two columns, one polar and one nonpolar installed in parallel in the gas chromatograph. Three types of neurones presented in this paper responded to one, two or three compounds for which the retention times were determined in both column types. The chemical structures of the active components were determined on the basis of mass spectrometry linked to gas chromatography, indicating E-β-ocimene and β-myrcene as stimulants for neurone type 1, E,E-α-farnesene for neurone type 2 and homo-farnesene for neurone type 3. Re-testing authentic materials verified the identifications for the type 1 neurones. The results demonstrate a high specificity for the three types of neurones by strong responses to one or two structurally similar compounds out of hundreds present in a large variety of plants. The study exemplifies plant odour detection by narrowly tuned receptor neurones in a polyphagous moth species. [ABSTRACT FROM AUTHOR]

CETACEA, ENANTIOSELECTIVE catalysis, POLYCHLORINATED biphenyls, and TOXICOLOGY

Isomer-specific concentrations of 41 polychlorinated biphenyls (PCBs) and the enantiomeric ratios (ER) of nine chiral PCBs were determined in the liver of four cetacean species--Risso's dolphin (Grampus griseus), bottlenose dolphin (Tursiops truncatus), fin whale (Balaenoptera physalus), and long-finned pilot whale (Globicephala melaena)--found dead in the Mediterranean Sea. The total PCB concentration (sum of 41 congeners) ranged from 484 to 63,200 ng/g wet weight. The 2,3,7,8 tetrachlorodibenzo- p-dioxin (TCDD) toxic equivalents (TEQs), as defined by the World Health Organization (WHO), ranged from 4.3 to 1,454 pg/g wet weight. The contribution of mono-ortho PCBs was consistently higher than non-ortho PCB congeners, in whale species, whereas in dolphins this predominance was not so clear. The PCB profiles were dominated by congeners 138, 153, and 180 in almost all the investigated samples. Comparison of PCB profiles by using principal component analysis allowed to separate the species into different groups. Polychlorinated biphenyls 170 and 180 seem to be eliminated by the two whale species, and PCB 180 also seems to be eliminated by Risso's dolphins. The PCBs 95, 132, 149, and 176 revealed an enantiomeric excess of the second eluted enantiomer in almost all the cetaceans investigated, where 136 and 174 were racemic or almost racemic. It is the first time that an enantiomeric excess of PCB 84 and 91 has been reported in biological samples. Although it was only possible to calculate them in two dolphin liver samples, the high values of enantiomeric excess found are surprising (86.3 and 32% for PCB 91 and 84, respectively). [ABSTRACT FROM AUTHOR]

ACYLATION, QUINOLINE, AMINES, and HYDROGEN bonding

A significant acceleration of acyl transfer has been achieved on 8-acetoxy-2-oxazolinylquinoline in the presence of benzylamine. Comparison of the aminolysis by the new acylating reagent with that of 8-acetoxyquinoline and 8-acetoxyquinoline-2-carbonitrile has been carried out. The results of these experiments suggest that the proximity of a supplementary basic atom to the ester group increases the participation effect of the basic site mainly by formation of a possible second hydrogen bond. The association constant of benzylamine into the basic cavity of 8-methoxy-2-oxazolinylquinoline (Ka=80 M−1) has been measured by 1H NMR titration experiments. [Copyright &y& Elsevier]

PRINTING, MOLECULAR self-assembly, and MONOMOLECULAR films

A technique for generating a general screening platform consisting of dots of immobilized beads on silicon has been developed via self-sorting and -assembly of different kinds of beads. The dots are defined by a teflon-like film, which due to its hydrophobic characteristics also prevents cross-contamination of liquid from different dots. To enable functionalization of individual dots with different target molecules simultaneously a new way of microcontact printing has been explored where different target solutions are printed in parallel using one stamp. In order to show that this platform can be designed for both biochemical assays and organic chemistry, streptavidin-, amino- and hydroxy-functionalized beads have been self-sorted and -assembled both on separate and common platforms. The self-sorting and -arrangement are based on surface chemistry only, which has not previously been reported. Beads of different sizes and material have successfully been immobilized in line patterns as narrow as 5 μm. Besides silicon, quartz and polyethylene have also been used as substrates. [Copyright &y& Elsevier]

STEREOCHEMISTRY and ENANTIOSELECTIVE catalysis

For the description of the stereoselectivity of (bio)catalytic asymmetric reactions which may proceed via different regio- or stereo-isomeric pathways (e.g. catalysed by epoxide hydrolases, dehalogenases, sulfatases or glycosidases), a parameter ‘RI’ (Retention–Inversion ratio) was introduced in analogy to the Enantiomeric Ratio (E), which describes enantioselectivity. A computer program was developed for the treatment of the kinetics of such single-step processes, which offer the potential of deracemization, i.e. a single stereoisomeric product is formed from a racemate in an enantioconvergent fashion. By analysis of experimentally determined progress curves of the enantiomeric excess of substrate and product (e.e.S, e.e.P, respectively) and the conversion (c), relative first-order rate constants ki, the enantioselectivity (E) and the RI ratio (RI) can be determined; in addition, processes can be simulated based on assumed ki values. [Copyright &y& Elsevier]

NATURAL products, HYDROLYSIS, and EPOXY compounds

A short chemoenzymatic route to two natural products—the first, a constituent of Jamaican rum and the second the (+)-antipode of the gibberelin synergist (−)-Pestalotin—was accomplished based on an enzyme-triggered cascade-reaction. Thus, a racemic halomethyl oxirane was hydrolyzed by bacterial epoxide hydrolases to furnish the corresponding vic-halomethyl-diol, which underwent spontaneous ring-closure to furnish an epoxy alcohol in up to 93% e.e. and ≥99 d.e. Due to the fact that this process was enantioconvergent, the occurrence of the undesired enantiomer was entirely avoided. [Copyright &y& Elsevier]

ESTRONE, CHLOROFLUOROCARBONS, and IRRADIATION

A rapid and efficient deuteration procedure was developed for estrone. Irradiation of estrone in CF3COOD in a microwave oven gave [2,4,16,16-2H4]-estrone in 95% yield. Ultrasound and CF3COOD reflux deuterations of estrone were also studied. [Copyright &y& Elsevier]

COMBINATORIAL chemistry, SOLID-phase analysis, and MICROWAVE heating

Recent advances in microwave-assisted combinatorial chemistry include high-speed solid-phase and polymer-supported organic synthesis, rapid parallel synthesis of compound libraries, and library generation by automated sequential microwave irradiation. In addition, new instrumentation for high-throughput microwave-assisted synthesis continues to be developed at a steady pace. The impressive speed combined with the unmatched control over reaction parameters justifies the growing interest in this application of microwave heating. [ABSTRACT FROM AUTHOR]

GERMACRENE, OVIPARITY, TOBACCO budworm, BUD-moth, OLFACTORY receptors, NEURONS, and ANTENNAE (Biology)

The sesquiterpene germacrene D (GD) activates a major type of olfactory receptor neuron on the antennae of the heliothine moths. In Heliothis virescens females, 80% of the recordings have shown activity of one neuron type responding with high sensitivity and selectivity to GD. With the aim of determining the behavioural significance of this sesquiterpene, we have used a two-choice wind-tunnel to study the preference of mated H. virescens females for host plants with and without (-)-GD added. Tobacco plants containing dispensers with low release rate of (-)-GD had a greater attractiveness than tobacco plants without this substance. In addition, a significant increase of oviposition was found on the plants with (-)-GD. [ABSTRACT FROM AUTHOR]

ESTERS, ENANTIOSELECTIVE catalysis, and ENANTIOMERS

Enantioselective biohydrolysis of sec-alkyl sulfate esters using a bacterial alkylsulfatase from Rhodococcus ruber DSM 44541 proceeded in a stereoselective fashion though inversion of configuration. Thus, from racemic substrates, the corresponding (R)-enantiomers were hydrolyzed selectively to furnish the corresponding sec-alcohol and non-reacted sulfate ester, both of (S)-configuration, which represents a homochiral product mixture. The enantioselectivities were found to depend on the substrate structure and were optimal for sec-sulfate esters in the ω-1 position (up to E=21). Since the enzyme was inactive on prim-sulfate esters, it can be classified as a sec-alkylsulfatase [EC 3.1.6.X]. [Copyright &y& Elsevier]

ESTERS, HYDROLYSIS, and ENANTIOMERS

The Enantioselectivity of the biohydrolysis of sec-alkyl sulfate esters using a bacterial alkylsulfatase from Rhodococcus ruber DSM 44541 was dramatically enhanced in presence of additives (‘enhancers’) such as carbohydrates, polyethylene glycol, detergents, metal ions and through enzyme immobilization. In presence of iron, the E value for the kinetic resolution of (±)-3- and (±)-4-octyl sulfate was improved from E=3.9 to ≥200 and E=1.1 to 10, respectively. [Copyright &y& Elsevier]

OXAZOLES, CATALYSTS, and LIGANDS (Biochemistry)

Metal complexes of chiral oxazoline derivatives immobilized on soluble as well as insoluble supports serve as versatile asymmetric catalysts in a variety of applications. In a few cases recovery and reuse of the chiral ligands have been achieved. [Copyright &y& Elsevier]

POLYTEF, BUFFER solutions, and LIGHT emitting diodes

The polytetrafluoroethylene (Teflon) was utilized as buffer layer to improve the performance of organic light emitting diodes (OLEDs). In the ITO/Teflon/N,N′-diphenyl-N,N′-(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD)/tris(8-hydroxy-quinoline) aluminum (Alq3)/Ca/Ag device, the Teflon film helped to enhance the hole tunneling injection and effectively impede indium diffusion from the ITO electrode. Compared with the devices without Teflon, the turn-on voltage was lowered by 1.5 V due to the introduction of Teflon buffer, and the optimized devices exhibited a luminous efficiency double that of the devices without Teflon layer, and the device lifetime proved to be dramatically increased. [Copyright &y& Elsevier]

KERATIN, SHEEP, and PROTEOGLYCANS

Recently, we reported the isolation and partial characterization of keratan sulphate (KS) from sheep brain. In this study, a panel of monoclonal antibodies (Mab) recognizing epitopes within KS chains and core proteins of KS-containing proteoglycans were used to detect, by immunoblotting, antigenically related molecules extracted from cerebrum, cerebellum and brainstem, respectively. Although the intensity of labelling varied with each of the antibodies, the brain KSPGs were recognized by all the monoclonals used, confirming the presence of KS side chains, which react with the Mabs: 5-D-4, EFG-11, EFG-4, I22, as also the presence of KSPGs related to phosphacan-KS (3H1 proteoglycan). Extracts of all the three brain areas could bind both anti-KS and anti-core protein Mabs, as also anti-HNK-1 monoclonal antibody. Binding was sensitive to keratanases degradation in the cerebrum and brainstem except cerebellum where the presence of a large molecular size hybrid CS/KSPG bearing KS chains partially resistant to keratanases was identified. This population reacts only with 5-D-4, EFG-11 and EFG-4 antibodies. Furthermore, the presence of HNK-1 epitope in CSPGs was detected in the cerebellum and brainstem. In contrast, in the cerebrum the coexistence of HNK-1 epitope and KS in KSPGs was identified. These data suggest that the KSs of sheep brain are part of proteoglycans containing protein and KS antigenic sites related to those of corneal and cartilage KSPG, as also of the brain proteoglycan phosphacan-KS. [Copyright &y& Elsevier]

AEROSOLS and ATMOSPHERIC chemistry

Atmospheric aerosols play a central role in climate and atmospheric chemistry. Organic matter frequently composes aerosol major fraction over continental areas. Reactions of natural volatile organic compounds, with atmospheric oxidants, are a key formation pathway of fine particles. The gas and particle atmospheric concentration of organic compounds directly emitted from conifer leaf epicuticular wax and of those formed through the photooxidation of α- and β-pinene were simultaneously collected and measured in a conifer forest by using elaborated sampling and G/ MS techniques. The saturation concentrations of acidic and carbonyl photooxidation products were estimated, by taking into consideration primary gas- and particle-phase organic species. Primary organic aerosol components represented an important fraction of the atmospheric gasphase organic content. Consequently, saturation concentrations of photooxidation products have been lowered facilitating new particle formation between molecules of photooxidation products and semi-volatile organic compounds. From the measured concentrations of the abovementioned compounds, saturation concentrations (C[sub sat, i]) of α- and β-pinene photooxidation products were calculated for nonideal conditions using a previously developed absorptive model. The results of these calculations indicated that primarily emitted organic species and ambient temperature play a crucial role in secondary organic aerosol formation. [ABSTRACT FROM AUTHOR]

DYNAMICS and ACETONE

Whole lyophilised cells of Rhodococcus ruber DSM 44541 were employed for the oxidative kinetic resolution of sec-alcohols using acetone as hydrogen acceptor. The enantioselectivity of this process could be controlled effectively by introducing C&z.sbnd;C multiple bonds into substrates, which were inefficiently recognised, in particular short-chain (ω-1)-alcohols and (ω-2)-analogs. Thus, the enantioselectivities of rac-2-pentanol (E=16.8) and rac-3-octanol (E=13.3) were significantly improved by introducing a C&z.dbnd6;C bond adjacent to the alcohol moiety to give racemic (E)-pent-3-en-2-ol and 4-(E)-octen-3-ol, which were resolved with excellent selectivities (E >100 and 50, respectively). In addition, it was found that high stereodifferentiation between the E- and Z-configured double bonds occurred, as the corresponding (Z)-isomers were not converted. Similar selectivity-enhancing effects were observed with acetylenic analogs. [Copyright &y& Elsevier]

COUPLING constants and PROTONS

A new method for heteronuclear X-filtering is presented, which relies on repetitive applications of 90°(1H)–τ(1/41JHC)–180°(1H,13C)–τ(1/41JHC)–90°(1H,13C)–PFG building blocks employing gradient-mediated suppression of magnetization built up for directly heteronuclear coupled protons. Thereby, a range of heteronuclear coupling constants can be suppressed by varying the delays of scalar coupling evolution both within and between individual transients. To achieve efficient destruction of 13C-coupled protons in macromolecular systems, the scalar coupling evolution delays were optimized using simulated annealing by including transverse relaxation effects. With a combination of regular hard pulses, delays and pulsed field gradients only, this method yields sufficient X-filtering to allow the observation of intermolecular nuclear overhauser effects in a molecular complex consisting of a 13C, 15N double-labeled, and an unlabeled protein. This is achieved by exciting magnetization of 12C- and 14N-bound protons and detecting 13C-bound 1H magnetization in a 3D 13C-filtered, 13C-edited NOESY–HSQC experiment. The method is tested on the 18 kDa homodimeric bacterial antidote ParD. [Copyright &y& Elsevier]

AMINO alcohols and CHEMICAL reagents

A large set of syn- and anti-1,2-amino alcohols has been synthesized. Upon comparison of the CH¯O and CH¯N 1H NMR shifts a general trend has been observed, making it possible to determine the relative configuration of 1,2-amino alcohols without derivatization or shift reagents. [Copyright &y& Elsevier]

AMINO alcohols and LIGANDS

(R,R)-Threoninol was prepared in one step from l-threonine in 86% isolated yield. The product was regioselectively transformed into 2,2-bis[(4R,5R)-4-(hydroxymethyl)-5-methyl-1,3-oxazolin-2-yl]propane in 42% isolated yield. [ABSTRACT FROM AUTHOR]

AMINO acids and ORGANIC synthesis

Six chiral amino sulfides have been synthesised from the amino acids phenylalanine, phenylglycine and valine. These amino sulfides were used as chiral ligands in the asymmetric addition of n-butyllithium and metyllithium to various aldehydes at low temperatures. The highest stereoselectivities were obtained with benzaldehyde, resulting in 1-phenyl-1-pentanol and 1-phenyl-1-ethanol in enantiomeric excesses of >98.5 and 95%, respectively. These stereoselectivities were significantly higher than those induced by the ether analogues. [Copyright &y& Elsevier]

ODORS, PLANTS, PISSODES, GAS chromatography, ALCOHOL, and CLUSTER pine

Plants release complex mixtures of volatiles important in the interaction with insects and other organisms. In the search for compounds that contribute to the perception of odour quality in the weevil Pissodes notatus, single olfactory receptor neurones on the antennae were screened for sensitivity to naturally produced plant volatiles by the use of gas chromatography linked to single cell recordings. We here present 60 olfactory neurones responding to 25 of the numerous compounds released by host and non-host plants. All the neurones show high selectivity and are classified into 12 distinct types. The two most abundant types respond to α-pinene, β-pinene, and 3-carene (n=17), and to isopinocamphone and pinocamphone (n=17), respectively. Other neurone types respond to limonene (n=9), β-phellandrene (n=3), and fenchone (n=4). Responses to β-caryophyllene (n=1) and to ethanol (n=4) are also shown. Except for two pairs, the neurone types do not show overlap of the molecular receptive range. The active compounds are present in the host, Pinus pinaster, as well as in non-hosts, supporting the idea that plant odour quality is mediated by the ratio of the compounds rather than specific odorants. [ABSTRACT FROM AUTHOR]

PERESKIA and ALCOHOL dehydrogenase

The organic solvent-stable redox-system of Rhodococcus ruber DSM 44541, which allows the efficient oxidation/reduction of sec-alcohols/ketones at the expense of acetone/2-propanol, respectively, as cosubstrate was optimized with respect to a maximum of alcohol dehydrogenase activity during cell growth. Comparison of the fermentation of R. ruber DSM 44541 in shake flasks cultures (1 l flask with 250 ml medium) and in a bioreactor (15 l with 10 l working volume) revealed that the desired organic solvent-stable alcohol dehydrogenase activity reached its maximum during the log phase for the bioreactor. In contrast, in shake flasks the maximum of activity was reached during the stationary phase. [Copyright &y& Elsevier]

ESTROGEN and ESTRADIOL

The estrogen metabolite 2-methoxyestradiol was synthesized from estradiol bis-THP-ether which was 2-hydroxylated using the superbase LIDAKOR, trimethyl borate, and H2O2, then methylated and deprotected to obtain 2-methoxyestradiol in three steps and 61% yield. 2-Hydroxyestradiol was obtained by deprotecting the 2-hydroxyestradiol bis-THP-ether from the first step. [Copyright &y& Elsevier]

LEWIS acids, AMMONIUM, and YLIDES

An investigation of the Lewis acid mediated [2,3]-sigmatropic rearrangement of allylic ammonium ylides has been conducted by employing various bases and boron Lewis acids. Using BBr3 together with the phosphazene base 6, various allylic amines could be rearranged in good yields with low to excellent diastereoselectivity. [Copyright &y& Elsevier]

CHITOSAN and FOURIER transform infrared spectroscopy

The surface of chitosan films was modified using acid chloride and acid anhydrides. Chemical composition at the film surface was analyzed by attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). ATR-FTIR data verified that the substitution took place at the amino groups of chitosan, thus forming amide linkages, and the modification proceeded to the depth at least 1 μm. Choices of molecules substituted at the amino groups of the glucosamine units did affect the hydrophobicity of the film surface, as indicated by air–water contact angle analysis. The surface became more hydrophobic than that of non-modified film when a stearoyl group (C17H35CO&z.sbnd;) was attached to the films. The reaction of chitosan films with succinic anhydride or phthalic anhydride, however, produced more hydrophilic films. Selected modified films were subjected to protein adsorption study. The amount of protein adsorbed, determined by bicinchoninic acid (BCA) assay, related to the types of attached molecules. The improved surface hydrophobicity affected by the stearoyl groups promoted protein adsorption. In contrast, selective adsorption behavior was observed in the case of the chitosan films modified with anhydride derivatives. Lysozyme adsorption was enhanced by H-bonding and charge attraction with the hydrophilic surface. While the amount of albumin adsorbed was decreased possibly due to negative charges that gave rise to repulsion between the modified surface and albumin. This study has demonstrated that it is conceivable to fine-tune surface properties which influence its response to bio-macromolecules by heterogeneous chemical modification. [Copyright &y& Elsevier]

MOLYBDENUM, VANADIUM, MICROCLUSTERS, and CRYSTALLOGRAPHY

Two novel trimetallic nanocluster complexes, {MoVI6MoV2VIV8O40(PO4)[Co(phen)2(H2O)]2}[Co2(phen)2(OH)2(H2O)4]1/2 (1) (phen = 1,10-phenanthroline) and {MoVI5MoV3VIV8O40(PO4)[Co(phen)(en)(H2O)]2}[Co(phen)3] ·1.5H2O (2) (phen = 1,10-phenanthroline, en = ethylenediamine), which are the first examples of mixed molybdenum-vanadium polyoxoanion bridged cluster complexes, have been hydrothermally prepared and characterized by X-ray crystallography. [ABSTRACT FROM AUTHOR]

PYRIDINIUM compounds and SOLID-phase synthesis

Pyridinium chlorochromate adsorbed on neutral alumina (PCC-Al2O3) under solvent-free conditions has been found to oxidize primary aliphatic alcohols to alkyl alkanoates whereas primary benzylic and primary allylic alcohols produce the corresponding aldehydes. Secondary aliphatic and aromatic alcohols produce ketones without isomerization and polymerization of double bonds, overoxidation and other side-reactions. [Copyright &y& Elsevier]

MOTHS, OLFACTORY nerve, INSECT food, SESQUITERPENES, TERPENES, and COMPARATIVE physiology

Specificity of olfactory receptor neurones plays an important role in food and host preferences of a species, and may have become conserved or changed in the evolution of polyphagy and oligophagy. We have identified a major type of plant odour receptor neurones responding to the sesquiterpene germacrene D in three species of heliothine moths, the polyphagous Heliothis virescens and Helicoverpa armigera and the oligophagous Helicoverpa assulta. The neurones respond with high sensitivity and selectivity to (–)-germacrene D, as demonstrated by screening via gas chromatography with numerous mixtures of plant volatiles. Germacrene D was present in both host and non-host plants, but only in half of the tested species. The specificity of the neurones was similar in the three species, as shown by the "secondary" responses to a few other sesquiterpenes. The effect of (–)-germacrene D was about ten times stronger than that of the (+)-enantiomer, which again was about ten times stronger than that of (–)-α-ylangene. Weaker effects were obtained for (+)-β-ylangene, (+)-α-copaene, β-copaene and two unidentified sesquiterpenes. The structure-activity relationship shows that the important properties of (–)-germacrene D in activating the neurones are the ten-membered ring system and the three double bonds acting as electron-rich centres, in addition to the direction of the isopropyl-group responsible for the different effects of the germacrene D enantiomers. [ABSTRACT FROM AUTHOR]

FURANS and NATURAL products

The synthesis of 5- and 3-(1′-hydroxyalkyl)-substituted 5H-furan-2-ones 4a–d and 8a–d as well as 5-alkylidene-5H-furan-2-ones 5a–d is described. A study of the structure–activity relationship of these furanone-based natural product analogues towards two different quorum sensing systems is reported. Although the synthesized compounds are not as potent quorum sensing inhibitors as some natural counterparts and a synthetic analogue hereof, interesting structure–activity relationships are seen. [Copyright &y& Elsevier]

ENANTIOMERS, STEREOCHEMISTRY, and ORGANIC synthesis

A single enantiomer of a (stereo)chemically labile allylic-homoallylic alcohol was obtained in 91% e.e. and 96% yield from the racemate by employing a lipase-catalysed kinetic resolution coupled to in situ inversion under carefully controlled (Mitsunobu) conditions in order to suppress side reactions, such as elimination and racemisation. This technique was successfully applied to an enantio-convergent asymmetric total synthesis of the algal fragrance component (S)-dictyoprolene. [Copyright &y& Elsevier]

THIOPHENES, CHEMICAL reagents, and DITHIOLE

A detailed study of the reactions of phosphorus pentasulfide and Lawesson''s reagent with a series of 4,5-bis(RCOCH2S)-1,3-dithiole-2-thiones (R=Ph, 4-MeOC6H4, 4-Br C6H4, Me) has been carried out. These reactions lead to fusion of either an unsaturated 1,4-dithiin ring or a thiophene to the dithiole; the former in higher yield, while the latter is a significant product in the reactions with Lawesson''s reagent; as well as small amounts of minor products. A mechanistic rationalization of these products is discussed in some detail. The new fused dithioles have been converted to novel series of fused TTF derivatives. [Copyright &y& Elsevier]

KETONES, ACETONE, OXIDATION, and ORGANIC compounds

For the development of a ‘green’ oxidation method, the transformation of 4-(p-hydroxyphenyl)butan-2-ol (rhododendrol) into 4-(p-hydroxyphenyl)butan-2-one (raspberry ketone) was used as a model reaction. Different lyophilized cells of Rhodococcus spp. have been screened for their ability to perform the desired oxidation. Rhodococcus equi IFO 3730 and R. ruber DSM 44541 were able to use acetone as a hydrogen acceptor in a hydrogen transfer-like process. The oxidation can be performed at substrate concentrations up to 500 g/L. [Copyright &y& Elsevier]

DIELS-Alder reaction, CHEMICAL reactions, HETEROCYCLIC compounds, LEWIS acids, ACID-base chemistry, and ORGANIC chemistry

Asymmetric Diels-Alder reactions with 2H-azirines as dienophiles have been studied. Diastereoselective reactions with an enantiopure azirine 1b, bearing a chiral auxiliary, gave substituted biand tricyclic tetrahydropyridines in high yield and stereoselectivity, under the influence of a Lewis acid. The novel enantioselective [4+2] cycloaddition reaction of 3-benzyl-2H-azirine carboxylate with cyclopentadiene was investigated with various chiral Lewis acid complexes and provided the corresponding tetrahydropyridines in moderate to low yield and enantioselectivity. [ABSTRACT FROM AUTHOR]

HYDROLYSIS, BIOTRANSFORMATION (Metabolism), ETHYLENE oxide, and METABOLISM

Asymmetric biohydrolysis of trisubstituted terpenoid oxiranes (rac-1a–rac-3a) was accomplished by employing the epoxide hydrolase activity Rhodococcus and Streptomyces spp. Depending on the biocatalyst, the biohydrolysis proceeded in an enantio-convergent fashion and gave the corresponding vic-diols in up to 97% ee at conversions beyond the 50%-threshold. In order to avoid a depletion of the ee of product by further oxidative metabolism, bioconversions had to be conducted in an inert atmosphere with exclusion of molecular oxygen. The synthetic applicability of this method was demonstrated by the asymmetric total synthesis of the monoterpenoid coumarin (R)-(+)-Marmin in 95% ee. [Copyright &y& Elsevier]

TITANIUM dioxide, SOLAR cells, ETHER (Anesthetic), SURFACES (Technology), THIN films, and SOLID state physics

We report for the first time the preparation method of compact TiO2 film using titanium butoxide-petroleum ether solution, by means of dipping and sintering. Our estimation of the component of this thin film was confirmed by XPS test. Studies of AFM showed the influence of preparation condition upon surface morphology. The transmitted spectrum of this compact TiO2 film was also investigated, which presented an excellent transmittance of this film in the visible light region. We arrive at a conclusion, according to the I-V characteristics of solid-state Grätzel solar cells utilizing this kind of compact film, that this compact TiO2 film functions well in secluding the conducting substrate from the hole-conducting material. [ABSTRACT FROM AUTHOR]

SICK building syndrome, PRINCIPAL components analysis, PHYSIOLOGICAL effects of humidity, VOLATILE organic compounds, and INDOOR air pollution

In this study, we were able to separate buildings with high and low prevalence of sick building syndrome (SBS) using principal component analysis. The prevalence of SBS was defined by the presence of at least one typical skin, mucosal and general (headache and fatigue) symptom. Data from the Swedish Office Illness Study describing the presence and level of chemical compounds in outdoor, supply, and room air, respectively, were evaluated together with information about the buildings in six models. When all data were included the most complex model was able to separate 71% of the high prevalence buildings from the low prevalence buildings. The most important variable that separates the high prevalence buildings from the low prevalence buildings was a more frequent occurrence or a higher concentration of compounds with shorter retention time in the high prevalence buildings. Elevated relative humidity in supply and room air and higher levels of total volatile organic compounds in outdoor and supply air were more common in high prevalence buildings. Ten building variables also contributed to the separation of the two classes of low and high prevalence buildings. Principal component analysis (PCA) can be a tool to evaluate variables that may cause Sick Building Syndrome. The method is promising, but more development of the technique, and a deeper understanding of how different type and specificity of input variables influence the modeling result are needed before PCA can be used as a practical tool. [ABSTRACT FROM AUTHOR]

CARBOXYPEPTIDASES, GUANIDINE, PROPIONIC acid, and GUANIDINES

A series of 3-mercapto-propionic acid derivatives that function as reversible inhibitors of carboxypeptidase U have been prepared. We present a successful design strategy using cyclic, low basicity guanidine mimetics resulting in potent, selective and bioavailable inhibitors of carboxypeptidase U (TAFIa). [Copyright &y& Elsevier]

RESEARCH institutes, ORGANIC chemistry, ANNIVERSARIES, SCIENTISTS, and HETEROCYCLIC chemistry

Reports that the N. D. Zelinsky Institute of Organic Chemistry (IOC), a large scientific center in Russia in the field of organic chemistry, organic catalysis, and the chemistry of natural and biologically active compounds, has turned 70 years old on February 23, 2004. Institute's concentration of highly qualified scientists on its staff; Major scientific results achieved by several institute; Studies in heterocyclic chemistry.

HYDROLYSIS, SPECTRUM analysis, MASS (Physics), and MASS spectrometry

Primary amino groups of di- or triaminoaryl compounds add a remarkably stable dioxinyl-α-oxoketene affording bis- or tris-[trioxabicyclo[3.3.1]nona-3,7-dienyl (bridged bisdioxine)] systems which can be converted into the corresponding bis- or tris-[2,4,6,8-tetraoxadamantanes] by acidic hydrolysis. Stereochemical peculiarities as well as preliminary host–guest abilities of these molecules are investigated with aid of NMR-spectroscopy, an X-ray analysis and ESI-mass spectrometry. [Copyright &y& Elsevier]

ALCOHOL, OXIDATION, DEHYDROGENASES, ENZYMES, CARBONYL reductase, and PLANT cells & tissues

To improve the efficiency and applicability of biocatalytic redox-reactions for asymmetric ketone-reduction and enantioselective alcohol-oxidation catalyzed by nicotinamide-dependent dehydrogenases/reductases, several achievements for cofactor-recycling have been made during the last two years. First, the use of hydrogenases for NADPH recycling in a two enzyme system. Second, preparative transformations with alcohol dehydrogenases coupled with NADH oxidases for NAD+/NADP+ recycling. Third, an exceptional chemo-stable alcohol dehydrogenase can efficiently use i-propanol and acetone as cosubstrates for reduction and oxidation, respectively, in a single-enzyme system. Novel carbonyl reductases and dehydrogenases derived from plant cells are particularly suited for sterically demanding substrates. [Copyright &y& Elsevier]

MONOMOLECULAR films, GOLD, SCIENTIFIC experimentation, ORGANIC chemistry, TEACHING, and LABORATORIES

The article presents a report on green materials chemistry in the teaching laboratory. In developing new educational materials for a greener organic chemistry laboratory curriculum the scholars aimed to design new laboratory exercises that emphasized the applications of organic chemistry to complement recently introduced greener synthesis laboratories. In particular, laboratories that focus on organic materials chemistry were a high priority. Authors of this article have described a convenient experiment that demonstrates self-assembled monolayer chemistry, organic thin-film patterning and the use of molecular functionality to control macroscopic properties.