Analytical and Sensory Characterization of gamma- and delta-Thiolactones.
gamma-Thiolactones [5-alkyldihydro-2(3H)-thiophenones] and delta-thiolactones (6-alkyltetrahydro-2H-thiopyran-2-ones) were synthesized via isothiouronium salts by reaction of the corresponding oxygen-containing lactones with thiourea and hydrobromic acid. The identity of the compounds was confirmed by means of IR, MS, and (1)H and (13)C NMR. Separation of the enantiomers of the thiolactones was achieved by capillary GC using heptakis(2,3-di-O-methyl-6-O-TBDMS)-beta-cyclodextrin as stationary phase. The substitution of oxygen by sulfur induces tropical fruit notes, which are more pronounced for the delta-thiolactones. Odor thresholds are dependent on ring size and chain length.
Roling
I
Technische Universität München, Lehrstuhl für Allgemeine Lebensmitteltechnologie, Am Forum 2, D-85350 Freising-Weihenstephan, Germany, and Technische Universität München, Lehrstuhl für Organische Chemie und Biochemie, Lichtenbergstrasse 4, D-85748 Garching, Germany.
Schmarr
HG
Eisenreich
W
Engel
KH