One-Pot Controlled Reduction of Conjugated Amides by Sequential Double Hydrosilylation Catalyzed by an Iridium(III) Metallacycle

A single and accessible cationic iridium(III)metallacycle effectively catalyzes the one-pot sequential double hydrosilylation of challenging alpha,beta-unsaturated secondary and tertiary amides to afford, in a controlled and straightforward way, the corresponding reduced products, namely, the related secondary and tertiary amides and amines. The catalytic hydrosilylations of the conjugated amides described herein proceeded in good yields and high chemoselectivities. The critical silyl enolate, in other words silyl ketene aminal intermediate, has been observed and characterized by using control experiments, mass spectrometry and state of the art NMR analyses. The present achievements indicate a promising potential of catalysts based on metallacycles for future significant developments in one-pot multicatalytic synthesis and therefore the production of highly functionalized and complex organic molecules.