Cp2Fe-mediated electrochemical phosphinoylative cyclization of N-acrylohydrazides to phosphorylated pyrazolones.

Herein, we describe a mild Cp2Fe-mediated electrochemical phosphinoylation/cyclization cascade for the direct synthesis of diverse phosphorylated pyrazolones. This strategy enables the efficient coupling of open-chain hydrazones with secondary phosphine oxides under metal- and external-oxidant-free conditions, offering broad substrate scope, excellent chemoselectivity, scalability, and late-stage functionalization of complex drugs.