Preparation of optically active cyclohexenones: Chirons for the lipophilic moiety of flowery‐ and woody‐like odorant ketones

Abstract

Abstract Optically active 2,5,6,6‐ and 2,4,4,5‐tetraalkylcyclohex‐2‐en‐1‐ones ((+)‐ 2a – d and (−)‐ 5a – d ), important building blocks for flowery‐ and woody‐like odorants, have been prepared. Compounds (+)‐ 2a – d and (−)‐ 5a – d were obtained by ozonolysis of the corresponding cyclopentenic precursors, followed by intramolecular aldol condensation. Alternatively, enones (+)‐ 2a – d were reduced to the corresponding allylic alcohols ad converted to enones (‐)‐ 5a – d via acidic isomerization and oxidation. 13 C‐NMR assignments are presented.