Sc(OTf)3-Catalyzed Reaction of Bicyclo[1.1.0]butanes with Isatins toward Cyclobutene–Indolinone Scaffolds Bearing Contiguous Stereocenters

Herein, we report an Sc(OTf)3-catalyzed ring-opening addition reaction of 1,3-disubstituted bicyclo[1.1.0]butanes with substituted isatins. This reaction provides efficient access to functionalized cyclobutene derivatives bearing two contiguous chiral centers under mild conditions. The protocol exhibits a broad substrate scope, good functional group tolerance, good to excellent yields (up to 84%), and moderate to good diastereoselectivity (up to 12:1 dr).