Cobalt‐Catalyzed Regioselective Methylative Coupling of Internal Alkynes with Aldehydes/Aldimines

Comprehensive Summary Catalytic methylative coupling of internal alkynes and aldehydes/aldimines through regioselective oxidative cyclization promoted by a phosphine–Co complex is presented. Such process constitutes an unprecedented and unique approach for Co‐catalyzed generation of metallacycles that reversed inherent regiochemical biases to furnish a wide range of allylic alcohols and allylic amides bearing a tetrasubstituted alkene in up to 98% yield with high regioselectivity, representing a novel and general strategy for reversal of substrate‐controlled regioselectivity in metal‐catalyzed oxidative cyclization.