Photocatalytic strain-release cyclization of bicyclo[1.1.0]butanes with sulfoxonium ylides to access spirocyclic oxindoles.

Reported herein is a photochemical strategy for the construction of spiro-oxindoles via a radical acylmethylation and cyclization of bicyclo[1.1.0]butanes with sulfoxonium ylides. This protocol constitutes the first example of strained rings as radical acceptors with sulfoxonium ylides, featuring operational simplicity, mild reaction conditions, good functional group tolerance, and applicability to the late-stage functionalization of drug-like molecules.