Annulation Reaction of Vinyl/Propargyl Sulfonium Salts with Carbon Nucleophiles: Stereoselective Synthesis of Functionalized Bicyclo[3.1.0]hexane Scaffolds.

Stereoselective cascade annulation reaction of vinyl/propargyl sulfonium salts with C-nucleophiles enables rapid construction of functionalized bicyclo[3.1.0]hexanes, bearing contiguous stereocenters, in good yields. This transformation proceeds via a Michael addition reaction of a C-nucleophile to a vinyl/allenyl sulfonium system, followed by an intramolecular Corey-Chaykovsky-type reaction, and consequently affords structurally complex bicyclic frameworks. This operationally simple strategy provides an efficient entry to synthetically challenging and densely functionalized carbocyclic scaffolds under mild conditions.