Blue light enhanced Heck arylation at room temperature applied to allenes

An unprecedented visible light enhanced room temperature Heck reaction between aryl halides and allenyl tosyl amines is here reported. A simple catalytic system (Pd(OAc)2/PPh3) is employed to afford arylated vinyl pyrrolidines and piperidines. A broad scope with high tolerance towards functional groups is observed. Electronic effects play an important role in the efficiency of this process. Mechanistic studies, both experimental and computational, indicate no evidence for a radical mechanism and a pivotal role of light in promoting the carbo-palladation step.