Photoinduced Nickel-Catalyzed\nHomolytic C(sp<sup>3</sup>)–N Bond Activation of Isonitriles\nfor Selective Carbo- and\nHydro-Cyanation of Alkynes

The exploration of strong chemical bonds as synthetic\nhandles offers\nnew disconnection strategies for the synthesis of functionalized molecules\nvia transition metal catalysis. However, the slow oxidative addition\nrate of these covalent bonds to a transition metal center hampers\ntheir synthetic utility. Here, we report a C(sp<sup>3</sup>)–N\nbond activation strategy that bypasses thermodynamically challenging\n2e<sup>–</sup> or 1e<sup>–</sup> oxidative addition\nvia a distinct pathway in nickel catalysis. This strategy leverages\na previously unknown activation pathway of photoinduced inner-sphere\ncharge transfer of low-valent nickel(isonitriles), triggering a C(sp<sup>3</sup>)–N bond cleavage distal to the metal–ligand\ninteraction to deliver nickel(cyanide) and versatile alkyl radicals.\nUtilizing this catalytic strategy, the selective intermolecular 1,2-carbocyanation\nreaction of alkynes with alkyl isonitriles as both alkylating and\ncyanating agents can be achieved, delivering a wide array of trisubstituted\nalkenyl nitriles with excellent atom-economy, regio-, and stereoselectivity\nunder mild conditions. Furthermore, Markovnikov-selective hydrocyanation\nof aliphatic alkynes can be accomplished through the synergistic action\nof a photocatalyst utilizing isonitriles as the cyanation agents.\nMechanistic investigations support the photogeneration of low-valent\nNi(isonitrile) complexes that undergo photochemical homolysis of the\nC(sp<sup>3</sup>)–N bond to engage catalytic cyanation with\nalkynes.