Intramolecular cyclization of radicals generated from alpha-halomethylsulfonamides

A series of homologous alpha-sulfonamidyl radicals has been generated by re action of alpha-halomethyl precursors with tri-n-butyltin hydride under AIB N catalysis. The intramolecular cyclization Capability of these highly reac tive intermediates has been evaluated. Where possible, five-membered sultam s are formed by 5-exo transition states. The longer C-SO2 and SO2-NR2 bonds have little demonstrable effect on this pathway. In larger systems, howeve r, the 7-endo option predominates over the 6-exo alternative. A preparative ly useful route to sultams has emerged from this investigation.