Efficient β-lactam synthesis via 4-exo atom transfer radical cyclisation using CuBr(tripyridylamine) complex

The tripyridylamine copper(I) halide complex mediates the atom transfer radical cyclisation of bromo-enamides to give β-lactams exclusively with no formation of γ-lactams. Initial products 7 arise from 4-exo bromine atom transfer but elimination can be readily achieved by reaction with DBU to furnish alkenes 8 in high yields (92–98%).