Electrosynthesis of Oxazol‐2(3H)‐Ones and Diaroylhydrazines from 1,2‐Dicarbonyl Compounds and Arenediazonium Salts

Abstract

New five‐membered oxazol‐2(3H)‐one heterocycles and 1,2‐diaroylhydrazines are obtained in good yield when 1,2‐dicarbonyl substrates are reduced at the cathode in N‐methyl formamide/LiClO4 as solvent‐supporting‐electrolyte system, and in the presence of arenediazonium salts. Electrochemical pathways are presented to involve a) cascade reactions: hydrogen atom abstraction from a solvent molecule, radical coupling reaction with substrate intermediate, and intramolecular migration of a methylamino group, to provide oxazolones or b) surprising C−C bond cleavage in the substrate radical anion, assisted by a diazonium salt, that evolves to disubstituted arylhydrazides.