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

Liu, Zhaohong; Yang, Yong; Song, Qingmin; Li, Linxuan; Zanoni, Giuseppe; Liu, Shaopeng; Xiang, Meng; Anderson, Edward A et al. · Nat Commun · 2022

basic_science · Level V

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Abstract

The conversion of inexpensive aqueous ammonia (NH<sub>3</sub>·H<sub>2</sub>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<sub>3</sub>) to bind and inhibit metal catalysts. Herein, we report a chemoselective carbene N-H insertion of NH<sub>3</sub>·H<sub>2</sub>O using a Tp<sup>Br3</sup>Ag-catalyzed two-phase system. Coordination by a homoscorpionate Tp<sup>Br3</sup> ligand renders silver compatible with NH<sub>3</sub> and H<sub>2</sub>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.

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