- Stereoisomeric Flavor Substances, XII. - 3-Methyl-4-octanolide - "Quercuslactone, Whiskylactone" - Structure and Properties of the Stereoisomeres
-
Ethyl 3-methyl-4-oxooctanoate (2) has been synthesized by reaction of pentanal with ethyl crotonate.Reduction with NaBH4 and cyclization yields racemic cis/trans-3-methyl-4-octanolide 1 which is separated to racemic cis (1a*1a') and trans (1b*1b') isomers by liquid chromatography.From 1a*1a' and 1b*1b' the diastereomers isopropyl (3R,4R)-, (3S,4S)-, (3S,4R)-, and (3R,4S)-4--3-methyloctanoates (3-6) and the diastereomers isopropyl (3R,4R)-, (3S,4S)-, (3S,4R)-, and (3R,4S)-4--3-methyloctanoates (7-10) have been synthesized and then separated by liquid chromatography.The absolute configurations of 1a, 1a', 1b and 1b' were derived from 1H-NMR data of 3-6 and optical activity could be estimated after recyclization into the optically active lactones 1a, 1a', 1b, and 1b'.From 7-10 optically pure stereoisomers of 1 have been obtained in preparative scale.Sensory characteristics of the stereoisomers are given.
- Guenther, Claus,Mosandl, Armin
-
p. 2112 - 2122
(2007/10/02)
-