Pd-Catalyzed C(sp2)-H carbonylation of 2-benzylpyridines for the synthesis of pyridoisoquinolinones.

An efficient synthesis of pyridoisoquinolinones, through Pd-catalyzed carbonylative annulation of 2-benzylpyridines, has been developed. The pyridinyl moiety in the substrate acts as both a directing group and an internal nucleophile for sp2 C-H activation and pyridocarbonylation. The ready availability of 2-benzylpyridines as well as the operational practicality makes this transformation potentially useful for the synthesis of analogues of protoberberine alkaloids.