An efficient way for the N-formylation of amines by inorganic-ligand supported iron catalysis

The first example of an inorganic-ligand supported iron(III) catalysed coupling of formic acid and amines to form formamides is reported. The pure inorganic catalyst (NH₄)₃[FeMo₆O₁₈(OH)₆] (1), which consists of a central Fe^III single-atomic core supported within a cycle-shaped inorganic ligand consisting of six Mo^VIO₆ octahedra, shows excellent activity and selectivity, and avoids the use of complicated/commercially unavailable organic ligands. Various primary amines and secondary amines have been successfully transformed into the corresponding formamides under mild conditions, and the formylation of primary diamines has also been achieved for the first time. The Fe catalyst 1 can be reused several times without appreciable loss of activity.