Chemoselective carbene insertion into the N−H bonds of NH3·H2O

Abstract

AbstractThe conversion of inexpensive aqueous ammonia (NH3·H2O) into value-added primary amines by N−H insertion persists as a longstanding challenge in chemistry because of the tendency of Lewis basic ammonia (NH3) to bind and inhibit metal catalysts. Herein, we report a chemoselective carbene N−H insertion of NH3·H2O using a TpBr3Ag-catalyzed two-phase system. Coordination by a homoscorpionate TpBr3 ligand renders silver compatible with NH3 and H2O and enables the generation of electrophilic silver carbene. Water promotes subsequent [1,2]-proton shift to generate N−H insertion products with high chemoselectivity. The result of the reaction is the coupling of an inorganic nitrogen source with either diazo compounds or N-triftosylhydrazones to produce useful primary amines. Further investigations elucidate the reaction mechanism and the origin of chemoselectivity.