Oxidative cross-dehydrogenative coupling between N-aryl tetrahydroisoquinolins and 5H-oxazol-4-ones through two methodologies: copper catalysis or a metal-free strategy

A direct oxidative cross-dehydrogenative coupling (CDC) of N-aryl tetrahydroisoquinolins with 5H-oxazol-4-ones catalyzed by CuBr using air as the only oxidant has been developed, which could also proceed smoothly under a metal-free oxidative system with PhI(OAc)(2) as the oxidant. A series of alkylated tetrahydroisoquinolin derivatives were obtained in good yields and excellent diastereoselectivities.