An efficient and chemoselective iron catalyst for the hydrogenation of ketones

Iron complex 1 containing electronically coupled acidic and hydridic hydrogens catalyzes the hydrogenation of ketones under mild conditions. This hydrogenation catalyst shows high chemoselectivity for aldehydes, ketones, and imines, and isolated CC, CC, C-X, -NO2, epoxides, and ester functions are unaffected by the hydrogenation conditions. Mechanistic studies have established a reversible hydrogen transfer step followed by rapid dihydrogen activation. The same iron complex also catalyzes transfer hydrogenation of ketones.