Chemoselective reduction of imines and azobenzenes catalyzed by silver N-heterocyclic carbene complexes

Here, the first example of NHC (N-heterocyclic carbene) ligand-promoted reduction of imines and azobenzenes with a homogeneous silver catalyst is reported. PhSiH3 induced hydrogenation of imines and azobenzenes and the use of 1 mol% NHC-Ag precatalyst allow for the retention of numerous reducible functionalities and the compatibility of sensitive groups, offering a mild and practical method for amine preparation with a wide application range and especially high turnover numbers (up to 9500). It has also been demonstrated that the IPrAgCl/PhSiH3 combination is responsible for the selective C=O reduction of aldehyde and ketone analogues.