Selective C(sp³)–H Cleavage of Enamides for Synthesis of 2-Pyridones via Ligand-Enabled Ni–Al Bimetallic Catalysis

Abstract

Previously reported direct C–H functionalization reactions of enamides mainly occurred at vinylic C(sp2)–H bonds because of their relatively high reactivity, while less reactive β′-C(sp3)–H activation has been rarely explored. Herein we report a selective C(sp3)–H cleavage of N-formyl enamides without backbone modification, providing a series of 2-pyridones in 58–99% yields. A bifunctional phosphine oxide (PO) ligand-bridging Ni–Al bimetallic catalyst played key role in the reaction.