LMCT enabled photo-decarboxylative CN cross coupling of α, βunsaturated acids with pyrazoles

Abstract

Herein, an oxidative decarboxylative C-N cross coupling of α,β-unsaturated acids with pyrazoles is reported to access N-benzoylpyrazoles. This merging protocol employs Fe(III)-catalyzed LMCT for decarboxylation of cinnamic acids, which further proceeds for C-N bond formation via dehydrogenative coupling with pyrazole derivatives, including fomepizole drug under 456 nm light irradiation. Mechanistic investigations reveal direct involvement of aerial oxygen in the amide group of the desired products, which overcomes previously employed unstable benzoyl synthons, enabling a greener route towards N-benzoylpyrazoles synthesis with traceless byproducts CO2 and H2O.