Chiral Bicyclic Guanidine-Catalyzed Enantioselective Sulfenylation of Oxindoles and Benzofuran-2(3H)‑ones

A chiral bicyclic guanidine-catalyzed enantioselective sulfenylation of 3-substituted oxindoles to N-(sulfanyl)­succinimides has been developed. A series of unprecedented 3-sulfenylated oxindoles, such as 3-benzyl/alkyl-substituted 3-benzyl/alkyloxindoles, were obtained with high enantioselectivities (up to 98% ee). This methodology is also effective for the first asymmetric sulfenylation of benzofuran-2­(3H)-ones, providing 3-benzyl-3-benzylthio-substituted benzofuran-2­(3H)-ones with satisfactory results (up to 95% ee).