Acylation of Alkylidenecyclopropanes for the Facile Synthesis of α,β-Unsaturated Ketone and Benzofulvene Derivatives with High Stereoselectivity

[reaction: see text] A variety of substituted alpha,beta-unsaturated ketone and benzofulvene derivatives were readily prepared in good to excellent yields via the reaction of alkylidenecyclopropanes with various acyl chlorides in the presence of aluminum chloride. The stereochemistry of the acylation and cyclization is discussed.