Iridium-catalyzed chemoselective transfer hydrogenation of α, β-unsaturated ketones to saturated ketones in water

A chemoselective iridium-catalyzed transfer hydrogenation of α, β-unsaturated ketones was realized in water. The CC double bonds of 2-benzylidene indanones and analogues were hydrogenated exclusively catalyzed by an iridium complex (0.1 mol%) bearing a pyridine-imidazoline ligand, using a mixture of formic acid/triethyl amine (molar ratio: 5/2) as a hydrogen source in water. A series of 2-benzyl indanones and analogues were obtained with good functional group tolerance and good yields. The practicability of this approach is also demonstrated by a gram-scale synthesis.