Sodium Hypophosphite Assisted Ruthenium Catalyzed Reductive Amination under Mild Conditions

We report a catalytic method for reductive amination using sodium hypophosphite as a cheap, bulk-grade available, and environmentally friendly reductant. The use of CpRu(PPh3)2Cl allowed the reaction to proceed under mild conditions, affording products in preparative yields. The method demonstrated great tolerance for a wide range of functional groups. A set of mechanistic trials resulted in one of the possible catalytic species, the Ru-hydride complex, being identified by NMR. A plausible mechanism of the process was proposed.