Transition-metal-free halocarbocyclisation of acrylamides using K2S2O8

A novel and direct transition-metal-free oxidative halocarbocyclisation of acrylamides using inexpensive KX (X = I, Br, Cl) and K 2 S 2 O 8 has been developed. This methodology not only provides an efficient way to construct valuable halogenated oxindoles in good to excellent yields, but also represents a novel strategy for C–X and C–C bond formation.