Efficient and Selective Iron-Complex-Catalyzed Hydroboration of Aldehydes

An imine-coupled [Fe–N2S2]2 complex, prepared from a readily available benzothiazolidine ligand, catalyzes selectively the hydroboration of aliphatic and aromatic aldehydes at low catalyst loadings (0.1 mol %) using pinacolborane. Both mono- and disubstituted aromatic and aliphatic aldehydes are hydroborated selectively in the presence of ketones, nitriles, alkenes, amines, and halides. Reaction of the [Fe–N2S2]2 complex with CO and preliminary reaction progress kinetic studies point to a complex mechanism.