Lewis Acid Catalyzed [3+2] Annulations of γ‐Butyrolactam‐Fused Donor–Acceptor Cyclopropanes with Aromatic Aldehydes and Aldimines

Abstract

A series of γ‐butyrolactam fused donor–acceptor (D–A) cyclopropanes were synthesized, and their reactivities in Lewis acid catalyzed [3+2] annulations with aromatic aldehydes and aldimines were studied. A range of γ‐butyrolactam fused tetrahydrofurans and γ‐butyrolactam fused pyrrolidines containing four contiguous stereogenic centers were generated in good‐to‐excellent yields and with exclusive diastereoselectivities and high enantiospecificity under the catalysis of 1 mol‐% of Al(OTf) 3 .