Stereoselective addition of methylcuprates to a 2-formyl-cyclohexa-2,5-dienone system. A stereoselective total synthesis of racemic β-vetivone

Abstract

The ketone (2), obtained from racemic α-terpineol (3), was converted by a six-step sequence into the 2-formyl-cyclohexadienone (14) which reacted stereoselectively with several methylcuprates, possibly by formation of an intermediate of type (16); e.g. with the lithium methylbromocuprate-di-isobutylamine complex a 5 : 1 mixture of racemic β-vetivone (1) and 10-epi-β-vetivone (12) was obtained, after deformylation.