Chemoselective silylative reduction of conjugated nitriles under metal-free catalytic conditions: β-silyl amines and enamines

Abstract

Abstract The B(C<inf>6</inf>F<inf>5</inf>)<inf>3</inf>-catalyzed silylative reduction of conjugated nitriles has been developed to afford synthetically valuable β-silyl amines. The reaction is chemoselective and proceeds under mild conditions. Mechanistic elucidation indicates that it proceeds by rapid double hydrosilylation of the conjugated nitrile to an enamine intermediate which is subsequently reduced to the β-silyl amine, thus forming a new C(sp3)-Si bond. Based on this mechanistic understanding, a preparative route to enamines was also established using bulky silanes. Triple whammy: The B(C<inf>6</inf>F<inf>5</inf>)<inf>3</inf>-catalyzed silylative reduction of conjugated nitriles has been developed to afford synthetically valuable β-silyl amines. Based on the mechanistic understanding, a preparative route to enamines was also established using bulky silanes. The reaction is chemoselective, has a broad scope, and proceeds under mild reaction conditions. The mechanism of the triple hydrosilylation is discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim