Photoredox Catalytic Phosphine-Mediated Deoxygenative Hydroacylation of Azobenzenes with Carboxylic Acids

The convenient and precise preparation of N,N′-diarylhydrazides, especially from readily available raw materials, remains highly challenging. Here, a photoredox catalytic phosphine-mediated deoxygenative hydroacylation of azobenzenes with abundant and readily available carboxylic acids has been developed. With Ir[dF(CF3)ppy]2(dtbbpy)PF6 as the photocatalyst, the reactions proceeded smoothly in the presence of PPh3 under visible light irradiation, delivering various N,N′-diarylhydrazides in up to 92% yields. Mechanistic studies revealed that the reaction proceeds via photoredox catalysis and phosphoranyl-radical-mediated C–O bond cleavage of carboxylic acids.