Rh(III)-Catalyzed Regioselective Synthesis of Pyridines from Alkenes and α,β-Unsaturated Oxime Esters

α,β-Unsaturated O-pivaloyl oximes are coupled to alkenes by Rh(III) catalysis to afford substituted pyridines. The reaction with activated alkenes is exceptionally regioselective and high-yielding. Mechanistic studies suggest that heterocycle formation proceeds via reversible C-H activation, alkene insertion, and a C-N bond formation/N-O bond cleavage process.