Preparation of Campholenal Analogues: Chirons for the lipophilic moiety of sandalwood‐like odorant alcohols

In connection with structure‐activity relationship studies, analogues of campholenal ((+)‐ 4b ), an important building block for sandalwood‐like odorants, were prepared. The five‐membered‐ring analogues 4 were obtained by epoxidation of the corresponding α‐pinene derivatives 2 , followed by catalytic ZnBr 2 isomerisation ( Scheme 2 ). The six‐membered‐ring skeleton was obtained by ozonolysis of α‐campholenyl acetate ((−)‐ 14b ), followed by intramolecular aldol condensation ( Scheme 5 ). 13 C‐NMR assignments are given.