Organophotoredox assisted cyanation of bromoarenes via silyl-radical-mediated bromine abstraction.

The insertion of a nitrile (-CN) group into arenes through the direct functionalization of the C(sp2)-Br bond is a challenging reaction. Herein, we report an organophotoredox method for the cyanation of aryl bromides using the organic photoredox catalyst 4CzIPN and tosyl cyanide (TsCN) as the nitrile source. A photogenerated silyl radical, via a single electron transfer (SET) mechanism, was employed to abstract bromine from aryl bromide to provide an aryl radical, which was concomitantly intercepted by TsCN to afford the aromatic nitrile. A range of substrates containing electron-donating and -withdrawing groups was demonstrated to undergo cyanation at room temperature in good yields.