Stereoisomere Aromastoffe, XII. 3‐Methyl‐4‐octanolid – „Quercuslacton, Whiskylacton”︁ – Struktur und Eigenschaften der Stereoisomeren

Abstract

Durch Umsctzung von Pentanal mit Crotonsaure-ethylester wird 3-Mcthyl-4-oxooctansaure-ethylester (2) gebildet, der sich mit NaBH4 reduzieren und in saurer Losung zu racemischem cis/trans-3-Mcthyl-4-octanolid 1 cyclisieren la&. Das Synthesegemisch wird chromatographisch leicht in cis-( l a la') und trans-Isomere ( l b * lb') getrennt. Aus l a - 1110, 1065, 1020, 995, 970, 965, 935, 905, 800, 785, 745, 645 cm-'. -

A concise synthetic route to optically active cis-β,γ-disubstituted-γ-butyrolactones via tandem Michael–MPV reaction: new total synthesis of (−)-cis-whisky lactone and (−)-cis-cognac lactone

“…15b [a] D = À78.0 (MeOH)} and spectroscopic data of synthetic (À)-ciswhisky lactone 9 were identical with those reported in the literature. 16 According to the same synthetic procedure, we achieved asymmetric total synthesis of (À)-cis-cognac lactone 10 (Scheme 5). 15c,17…”

Chirality in flavor chemistry‐recent developments in synthesis and analysis

“…Radical addition of pentanal to ethylcrotonoate yields 3-methyl-4-oxooctanoic acid ethylester (41,42), similar to the method of Huang (43). By reduction with NaBH 4 and subsequent working up from acidic media, a mixture of racemic cis/trans diastereomers of "whisky lactone" was obtained, which were easily separated to racemic cis and trans diastereomers, respectively, by liquid chromatography (Scheme 5).…”

Influence of geographical location, site and silvicultural parameters, on volatile composition of Quercus pyrenaica Willd. wood used in wine aging

“…These compounds are mainly responsible for the flavor and taste of aged wines which implies an improvement in their organoleptic properties. Among volatile compounds found in oak wood, especially remarkable for their sensory impact are: cis-and trans-ˇ-methyl--octalactones, also known as oak lactones, a key compound in aged wines due to their oak or coconut flavor and low perception threshold (Abbott et al, 1995;Günther and Mosandl, 1986); vanillin and its derivatives, described as responsible for the vanillin flavor and small free phenols such as eugenol and guaiacol, characterized by spice and smoke flavors (Boidron et al, 1988;Díaz-Maroto et al, 2008). Several terpenic and norisoprenoid compounds have been also described in oak wood.…”