Hydrosilanes as Hydrogen Source: Iridium-Catalyzed Hydrogenation of N-Heteroarenes

A ligand- and base-free method for the catalytic synthesis of bioactive 1,2,3,4-tetrahydroquinolines via the homogeneous iridium-catalyzed hydrogenation of quinolines and related N-heteroarenes is reported. A catalytic reduction of N-heteroarenes employing low-cost and air-stable hydrosilane was demonstrated under mild conditions. This reaction is scalable and tolerable for sensitive functional groups, such as bromide, chloride, fluoride, ester, carboxylic acid, cyanogroup and nitro groups. This catalytic system provides a convenient, environmentally friendly and practical method to obtain a variety of 1,2,3,4-tetrahydroquinoline derivatives under mild reaction conditions.