Synthesis of 2,5-Disubstituted Pyrrolidines from N-Alkenyl and Alkynyl N-Benzoyloxysulfonamides Catalyzed by (CuOTf) 2 ･C 6 H 6

A new synthetic method of 2,5-disubstituted pyrrolidines is developed by the cyclization of unsaturated N-benzoyloxysulfonamides by $(CuOTf)_2{\cdot}C_6H_6$ in refluxing dichloroethane. Various N-4- and N-5-alkenyl and alkynyl N-benzoyloxysulfonamides are cyclized to give pyrrolidines. The cyclization proceeds via addition of sulfonamidoyl radicals to intramolecular unsaturated bonds or allylic hydrogen abstraction with the radical intermediates.