Palladium(II)-Catalyzed Intramolecular Oxidative C−H/C−H Cross-Coupling Reaction of C3,N-linked Biheterocycles: Rapid Access to Polycyclic Nitrogen Heterocycles

A Pd(II)-catalyzed intramolecular oxidative C–H/C–H cross-coupling has been developed for the direct construction of valuable polycyclic heteroarene scaffolds. From a retrosynthetic point of view, the strategic formation of a C–C bond via C(sp2)–H/C(sp2)–H dehydrogenative coupling across C3,N-linked biheterocyclic precursors may be useful in de novo syntheses of indole-derived natural products and pharmaceuticals. The reaction exhibited good functional group/heterocycle tolerance, and a proposed mechanism involving an azoylpalladium complex is also supported.