Potassium Amide-Promoted Direct Synthesis of α-Aryl Nitriles from α-Aryl Alkenes.

The synthesis of organic nitriles remains heavily dependent on methodologies that often involve transition-metal catalysts or toxic cyanide reagents, limiting their sustainability. Here, we report a cyanide- and transition-metal-free chemical looping strategy that converts α-aryl alkenes and ammonia (NH3) into α-aryl nitriles using potassium amide (KNH2) as a reaction mediator. The reaction initially proceeds via the formation of α-aryl nitrile potassium salts. Subsequent treatment of the potassium salts with NH3 liberates nitriles and regenerates KNH2, thereby closing the chemical loop. Combined experimental characterizations and computational results reveal an initial nucleophilic amide-mediated anti-Markovnikov addition followed by a K+-facilitated dehydrogenation process. Two synergistic effects stabilize the key carbanionic intermediates: carbanion-phenyl conjugation and tridentate coordination of K+. Owing to stronger conjugation among the phenyl rings, the central carbanion, and the cyano group, the product carbanion is energetically more stable than the precursor carbanion, which constitutes the thermodynamic driving force for the overall dehydrogenation. This atom-economical approach redefines alkali metal amides as versatile reagents for sustainable nitrogen-atom transfer.