Mechanistic studies on the N-formylation of amines with CO2 and hydrosilane catalyzed by a Cu–diphosphine complex

Abstract The reaction mechanism, reaction intermediates, and catalytically active species of the Cu–diphosphine-catalyzed N-formylation of amines (R 1 R 2 NH) with CO 2 and hydrosilane were investigated. The NMR and kinetic experiments show that the catalytically active species is a Cu-hydride–diphosphine complex, which was generated from the Cu precursor, diphosphine ligand, and hydrosilane. Isotopic experiments using 13 CO 2 and deuterated hydrosilane revealed the incorporation of the carbonyl group of CO 2 and the H atom of Si–H moiety into the formamide (R 1 R 2 NCHO) product. The formation of a Cu-formate species as an intermediate of the reaction was clarified by in situ 1 H and 13 C NMR studies.