Synthesis and analysis of thio-, thiono-, and dithio-derivatives ofwhiskey lactone

摘要

Cis- and trans-3-methyl-4-octanolide (1, whiskey lactones) were converted into their thio- (2), thiono-(3), and dithio- (4) derivatives by reaction with phosphorus pentasulfide. The reaction products were characterized by GC-mass spectrometry, H-1 NMR spectroscopy, and GC-olfactometry. Two-dimensional NOESY spectra showed that sulfur is incorporated into the ring with reversal of the absolute configuration at C-4, whereas substitution of the keto-oxygen atom by sulfur occurs with retention of ring configuration. The cis- and trans-pairs of 2, 3, and 4 were separated into enantiomers by GC on heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-beta -cyclodextrin and heptakis(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-beta -cyclodextrin as chiral stationary phases. GC-olfactometry revealed a sweet coconut-like odor for the cis-thio- and pleasant mushroom-like flavors for the cis-thiono- and trans-dithio-derivatives of whiskey lactone.