Organocatalytic Enantioselective (4+2) Annulation of Cyclopropane Carbaldehydes with 2-Mercapto-1-Arylethanones

Here, we report the organocatalytic enantioselective synthesis of dihydrothiopyran derivatives from trans racemic donor-acceptor cyclopropane carbaldehydes (DACCs) and 2-mercapto-1-arylethanone via formal thio (4+2) cycloaddition involving thia-Michael aldol condensation and annulation. Mechanistic studies indicate a typical kinetic resolution (KR) is involved in this transformation, which results in moderate yields and enantiomeric ratios. Remarkably, this method is characterized by its one-pot simplicity, mild reaction conditions, and resilience towards air and moisture interference. image