Intramolecular Cyclization of Radicals Generated from α-Halomethylsulfonamides

A series of homologous α-sulfonamidyl radicals has been generated by reaction of α-halomethyl precursors with tri- n -butyltin hydride under AIBN catalysis. The intramolecular cyclization capability of these highly reactive intermediates has been evaluated. Where possible, five-membered sultams are formed by 5-exo transition states. The longer C−SO 2 and SO 2 −NR 2 bonds have little demonstrable effect on this pathway. In larger systems, however, the 7-endo option predominates over the 6-exo alternative. A preparatively useful route to sultams has emerged from this investigation.