Expedient Access to 2,3-Dihyd ropyridines from Unsaturated Oximes by Rh(Ⅲ)-Catalyzed C-H Activation

摘要

α,β-Unsaturated oxime pivalates are proposed to undergo reversible C(sp~2)-H insertion with cationic Rh(Ⅲ) complexes to furnish five-membered metallacycles. In the presence of 1,1-disubstituted olefins, these species participate in irreversible migratory insertion to give, after reductive elimination, 2,3-dihydropyridine products in good yields. Catalytic hydrogenation can then be used to convert these molecules into piperidines, which are important structural components of numerous Pharmaceuticals.