Photoredox-Catalyzed Intermolecular Radical Addition to Allenamides: A Complementary Approach to Conjugated N-Acyliminium Formation.

An intermolecular radical addition, using photoredox catalysis, to allenamides is reported. This transformation synthesizes N-acyl-N’-aryl-N,N’-allylaminals, and proceeds by a conjugated N-acyliminium intermediate, that previously, has only been generated by electrophilic activation methods. The radical adds to the central carbon of the allene giving a conjugated N-acyliminium, that undergoes nucleophilic addition by arlyamines and alcohols.