Synthesis of the Insect Pheromone (2S,3S,7RS)-Diprionyl Acetate by Diastereoselective Protonation

Abstract

The insect pheromone (2S,3S,7RS)-diprionyl acetate (1) was prepared from (S,S)-2,3-dimethylcyclohexanone (2), which in turn was obtained by the 1,4-addition of lithium dimethylcuprate to (S)-(+)-carvone (3) and diastereoselective protonation of the resulting enolate with phenyl salicylate, followed by removal of the isopropenyl group and hydrogenation. Baeyer−Villiger rearrangement of (S,S)-2 and opening of the lactone (S,S)-8 with octyllithium provided the hydroxy ketone (S,S)-9, which was transformed into the target molecule (2S,3S,7RS)-1 by carbonyl olefination with Petasis’ reagent, acylation and hydrogenation.