| Abstract: | The synthesis of enantiomerically pure (+)‐ and (?)‐γ‐ionone 3 is reported. The first step in the synthesis is the diastereoisomeric enrichment of 4‐nitrobenzoate derivatives of racemic γ‐ionol 12 . The enantioselective lipase‐mediated kinetic acetylation of γ‐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 γ‐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 γ‐dihydroionones (?)‐(R)‐ 16 and (+)‐(S)‐ 17 , respectively, allowed us to assign unambiguously the absolute configuration of the γ‐ionones. |
