Chemoselective carbene insertion into the N-H bonds of NH 3 ·H 2 O.

The conversion of inexpensive aqueous ammonia (NH 3 ·H 2 O) into value-added primary amines by N-H insertion persists as a longstanding challenge in chemistry because of the tendency of Lewis basic ammonia (NH 3 ) to bind and inhibit metal catalysts. Herein, we report a chemoselective carbene N-H insertion of NH 3 ·H 2 O using a Tp Br3 Ag-catalyzed two-phase system. Coordination by a homoscorpionate Tp Br3 ligand renders silver compatible with NH 3 and H 2 O 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.