Sub-Room Temperature Transfer Hydrogenation of α,β-Unsaturated Ketones Using Methanol as a Hydrogen Source

Abstract

A chemoselective transfer hydrogenation of α,β-unsaturated ketones at sub-room temperature (15–25 °C) using methanol and an Ir(III) pyridylidene–indole catalyst is reported. The protocol offers broad substrate scope, gram-scale synthesis without chromatographic purification, and site-selective deuteration under reduced energy input. Mechanistic investigations, including kinetic, control, and isotope-labelling studies, support a concerted hydrogen transfer pathway facilitated by strong ligand σ-donation, offering a practical low-energy route to defined hydrogenated products.