- Influence of the chemical structure on odor qualities and odor thresholds in homologous series of alka-1,5-dien-3-ones, alk-1-en-3-ones, alka-1,5-dien-3-ols, and alk-1-en-3-ols
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Odor qualities and odor thresholds in air in homologous series of synthesized alk-1-en-3-ols and alka-1,5-dien-3-ols and their corresponding ketones were evaluated by gas chromatography-olfactometry. In the series of the alk-1-en-3-ols and alk-1-en-3-ones the odor quality changed successively from pungent for the compounds with five carbon atoms via metallic, vegetable-like for the six- and seven-carbon odorants to mushroom-like for the compounds with eight and nine carbon atoms. With further increase in chain length the mushroom-like impression decreased and changed to citrus-like, soapy, or herb-like. In both series, two odor threshold minima were found for the six-carbon and also for the eight- and nine-carbon odorants, respectively. In contrast to this, the odor qualities in the series of the (Z)- and (E)-alka-1,5-dien-3-ols and their corresponding ketones did not change significantly with geranium-like, metallic odors and an increasing mushroom-like odor note with increasing chain length. The lowest thresholds were found for the eight- and nine-carbon (Z)-compounds, respectively.
- Lorber, Katja,Schieberle, Peter,Buettner, Andrea
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p. 1025 - 1031
(2014/03/21)
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- Influence of the chemical structure on odor qualities and odor thresholds in homologous series of alka-1,5-dien-3-ones, alk-1-en-3-ones, alka-1,5-dien-3-ols, and alk-1-en-3-ols
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Odor qualities and odor thresholds in air in homologous series of synthesized alk-1-en-3-ols and alka-1,5-dien-3-ols and their corresponding ketones were evaluated by gas chromatography-olfactometry. In the series of the alk-1-en-3-ols and alk-1-en-3-ones the odor quality changed successively from pungent for the compounds with five carbon atoms via metallic, vegetable-like for the six- and seven-carbon odorants to mushroom-like for the compounds with eight and nine carbon atoms. With further increase in chain length the mushroom-like impression decreased and changed to citrus-like, soapy, or herb-like. In both series, two odor threshold minima were found for the six-carbon and also for the eight- and nine-carbon odorants, respectively. In contrast to this, the odor qualities in the series of the (Z)- and (E)-alka-1,5-dien-3-ols and their corresponding ketones did not change significantly with geranium-like, metallic odors and an increasing mushroom-like odor note with increasing chain length. The lowest thresholds were found for the eight- and nine-carbon (Z)-compounds, respectively.
- Lorber, Katja,Schieberle, Peter,Buettner, Andrea
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p. 1025 - 1031
(2015/04/22)
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- Scandium-catalyzed regio- and stereospecific methylalumination of silyloxy/alkoxy-substituted alkynes and alkenes
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(Chemical Equation Presented) Various alkynes and alkenes having a tethered ether group undergo methylalumination reactions with unprecedented regio- and stereoselectivity in the presence of a cationic half-sandwich alkylscandium species as a catalyst. The oxygen atom of the ether group plays an important role in controlling the selectivity, possibly by coordinating to the metal center. Even when a bulky tert-butyl(diphenyl)silyloxy group is used as the tether group, there is no loss of selectivity.
- Takimoto, Masanori,Usami, Saori,Hou, Zhaomin
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supporting information; experimental part
p. 18266 - 18268
(2010/04/25)
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- COMPOUNDS WITH A HERBAL ODOR VI. THE E ISOMERS OF THE STRUCTURAL ANALOGS OF LEAF ALCOHOL
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The E isomers of leaf alcohol and its structural analogs differing in the length of the carbon chain, the presence of substituents at various positions of the molecule, the position of the double bond, and replacement of the double bond by a three-membered ring were synthesized.Many representatives of the Z and E series have a herbal odor, and similarity is observed in the odor of the respective pairs of Z and E isomers.The proximity of the odor of the investigated compounds to the standard (leaf alcohol) is determined by the number of carbon atoms in their molecules.
- Vasil'ev, A. A.,Cherkaev, G. V.,Nikitina, M. A.
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p. 870 - 875
(2007/10/02)
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- New Oxyfunctionalization Capabilities for ω-Hydroxylases: Asymmetric Aliphatic Sulfoxidation and Branched Ether Demethylation
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Due to inherent difficulties in the chemical generation of aliphatic synthons, the stereo- and regioselective oxyfunctionalization of simple aliphatic substrates represents an area where chemical applications of biocatalysis would be particularly useful.The hydrocarbon monooxygenase from Pseudomonas oleovorans is a prototypical "ω-hydroxylase" known to carry out hydroxylation at the terminal methyl of alkanes as well as epoxidation of terminal olefins.It is now demonstrated that this enzyme system catalyzes stereoselective sulfoxidation of methyl thioether substrates, representing the first clear example of oxygenase-produced chiral aliphatic sulfoxides yet reported.In addition, it is shown that this enzyme system catalyzes oxygenative O-demethylation of branched alkyl methyl and branched vinyl methyl ethers to secondary alcohols and ketones, respectively.These findings establish new oxyfunctionalization capabilities, and thus a significantly expanded biotechnological potential, for the hydrocarbon monooxygenases.
- Katopodis, Andreas G.,Smith, Homer A.,May, Sheldon W.
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p. 897 - 899
(2007/10/02)
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- MODIFIED KNOEVENAGEL CONDENSATIONS. SYNTHESIS OF (E)-3-ALKENOIC ACIDS.
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Condensation of aliphatic aldehydes with a three molar excess of malonic acid and 0.001 mole piperidinium acetate in refluxing xylene, with continuous removal of the water formed, gave almost exclusively (E)-3-alkenoic acids, in good yield (60-85percent) and of high stereochemical purity (95-99percent).
- Ragoussis, Nikitas
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- A Short Total Synthesis of (+/-)-Gephyrotoxin-223AB
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(+/-)-Gephyrotoxin-223AB has been synthesized from 2-carbomethoxycyclopentanone in nine steps by a route utilizing the stereoselective homolytic cyclization of an alkenyl-substituted N-chloropiperidine.
- Broka, Chris A.,Eng, Kan K.
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p. 5043 - 5045
(2007/10/02)
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