Analytical and Sensory Characterization of the Stereoisomers of 3‑Mercaptocycloalkanones and 3‑Mercaptocycloalkanols

3-Mercaptocycloalkanones and 3-mercaptocycloalkanols (chain lengths C5–C7) were obtained by addition of thioacetic acid to the respective 2-cycloalken-1-ones and subsequent enzyme-mediated hydrolysis and reduction with LiAlH4, respectively. The stereoisomers were separated via capillary gas chromato...

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Veröffentlicht in:Journal of agricultural and food chemistry 2020-07, Vol.68 (27), p.7184-7193
Hauptverfasser: Wakabayashi, Motoko, Wakabayashi, Hidehiko, Riegel, Anja Devenie, Eisenreich, Wolfgang, Engel, Karl-Heinz
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Sprache:eng
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Zusammenfassung:3-Mercaptocycloalkanones and 3-mercaptocycloalkanols (chain lengths C5–C7) were obtained by addition of thioacetic acid to the respective 2-cycloalken-1-ones and subsequent enzyme-mediated hydrolysis and reduction with LiAlH4, respectively. The stereoisomers were separated via capillary gas chromatography using chiral stationary phases. Their configurations were determined based on 1H NMR data and enzyme-catalyzed kinetic resolutions. Odor thresholds and odor qualities were assessed by capillary gas chromatography/olfactometry. Compared to the analogous acyclic 4-mercapto-2-alkanones and 4-mercapto-2-alkanols, the cyclic polyfunctional thiols lacked fruity, tropical notes; the perceived odor properties ranged from cooked, roasted vegetables and meat types to onion-related notes. The odor thresholds of the enantiomers of the 3-mercaptocycloalkanones were mainly impacted by their ring size rather than their configuration. For the 3-mercaptocycloalkanols, the (S)-configuration at the stereogenic center bearing the thiol group and the relative configuration of the second asymmetric center with the hydroxyl group were of importance for low odor thresholds.
ISSN:0021-8561
1520-5118
DOI:10.1021/acs.jafc.0c03113