Determination of the Absolute Configurations and Sensory Properties of the Enantiomers of a Homologous Series (C6–C10) of 2-Mercapto-4-alkanones

July 30, 2019

Title

Determination of the Absolute Configurations and Sensory Properties of the Enantiomers of a Homologous Series (C6–C10) of 2-Mercapto-4-alkanones

Author

Christiane Kiske, Anja Devenie Riegel, Ronja Hopf, Anna KvindtIulia Poplacean,Tohru Taniguchi, Mahadeva M. M. Swamy, Kenji Monde, Wolfgang Eisenreich, Karl-Heinz Engel

Year

2019

Journal

Journal of Agricultural and Food Chemistry

Abstract

The enantiomers of a homologous series (C6–C10) of 2-mercapto-4-alkanones were obtained by lipase-catalyzed kinetic resolution of the corresponding racemic 2-acetylthio-4-alkanones. Their configurations were assigned via vibrational circular dichroism and 1H NMR anisotropy based methods. Odor thresholds and odor qualities were determined by capillary gas chromatography–olfactometry using chiral stationary phases. There were minima of the odor thresholds for the chain lengths C7 and C8. Except for chain length C8, the enantiomers of the other homologues showed similar odor thresholds. The odor qualities ranged from pungent (C5) to mushroom (C9 and C10) and were similar to those known for the corresponding 1-alken-3-ones with one less C atom. In contrast to their positional isomers (4-mercapto-2-alkanones), the investigated 2-mercapto-4-alkanones do not meet the requirements of a “tropical olfactophore” (i.e., compounds possessing a 1,3-oxygen-sulfur functionality and specific arrangements of the substituents).

Instrument

FVS-6000

Keywords

Vibrational circular dichorism, 2-mercapto-4-alkanones, absolute configuration, 1H, NMR spectroscopy, odor threshold, odor quality