P(III)-Mediated Formal Reductive N–H Bond Insertion Reaction of Hydrazones to α-Keto Esters

A diazo-, metal-, and base-free multi-substituted hydrazone synthesis via a formal reductive N–H bond insertion reactions of hydrazones to α-keto esters has been developed. The protocol features a broad substrate scope and good functional group tolerance, providing N–H bond insertion products in moderate to excellent yields. Moreover, P(III)-mediated N–H functionalization of pharmaceutical containing hydrazone moiety was also successfully achieved.