The synthesis of enantiometically pure (+)- and (-)-gamma -ionone 3 is reported. The first step in the synthesis is the diastereoisomeric enrichment of 4-nitrobenzoate derivatives or racemic gamma -ionol 12. The enantioselective lipase-mediated kinetic acetylation of gamma -ionol 13b afforded the acetate 14 and the alcohol 15, which are suitable precursors of the desired products (-)- and (+)-3, respectively. The olfactory evaluation of the gamma -ionone isomers shows a great difference between the two enantiomers both in fragrance response and in detection threshold. The selective reduction of (-)-3 and (+)-3 to the gamma -dihydroionones (-)-(R)-16 and (+)-(S)-17, respectively, allowed us to assign unambiguously the absolute configuration of the gamma -ionones.
A straightforward enantioselective synthesis of both enantiomers of the title compounds is described starting from enantiopure methyl (2S,6R)- or (2R,6S)-cis-2-hydroxy-gamma-cyclogeraniate. These versatile building blocks are obtained by biomimetic cyclization of methyl (6S)- or (6R)-(Z)-6,7-epoxy-7-methyl-3-(trimethylsilyl)methyl-2-octenoate, respectively. The chiral information was encoded by a highly regioselective Sharpless asymmetric dihydroxylation of the corresponding diene. (C) 2002 Elsevier Science Ltd. All rights reserved.
Absolute Konfiguration der enantiomeren ?-Cyclogeraniums�Uren, ?-Cyclogeraniale, ?-Jonone, ?-Jonone, ?-und ?-Carotine
作者:Richard Buchecker、Robert Egli、Helen Regel-Wild、Christoph Tscharner、Conrad Hans Eugster、Gerald Uhde、G�nther Ohloff
DOI:10.1002/hlca.19730560739
日期:1973.11.7
AbstractBy chemical correlation with manool and ambrein the absolute configurations of the enantiomeric α‐cyclogeranic acids, α‐cyclogeranials, α‐ionones and α‐ and ϵ‐carotenes have been elucidated.
Oritani, Takayuki; Yamashita, Kyohei, Agricultural and Biological Chemistry, 1987, vol. 51, # 5, p. 1271 - 1276
作者:Oritani, Takayuki、Yamashita, Kyohei
DOI:——
日期:——
ORITANI, TAKAYUKI;YAMASHITA, KYOHEI, AGR. AND BIOL. CHEM., 51,(1987) N 5, 1271-1275