9-Fluorenone Catalyzed Visible Light Oxidation of Hydrazides: An Efficient Route for the Synthesis of N,N′-Diacylhydrazines Derivatives

A visible light-mediated oxidative coupling of hydrazides into corresponding N,N'- diacylhydrazines using a commercially available and low-cost metal-free photocatalyst was reported. The versatility of the reaction has been demonstrated across a broad spectrum of functional groups present in hydrazides. Interestingly, the developed methodology was utilized to synthesize symmetrical and unsymmetrical N,N'-diacylhydrazines in moderate yields. Density Functional Theory (DFT) calculations, along with control reactions and quenching studies, provide evidence supporting the proposed mechanism, favoring the photoredox pathway. Additionally, NMR and UV-Vis studies confirmed the generation of H2O2 in the reaction mixture, which strengthens the proposed mechanism. To our knowledge, this is the first report for the conversion of hydrazides to N,N'-diacylhydrazines using 9-fluorenone as an organic photoredox catalyst.