Silyl Radical–Mediated Photocatalytic Decyanation of α-Monosubstituted Malononitriles

Abstract This manuscript represents a photocatalytic decyanation of α-monosubstituted malononitriles using a silyl boronic acid pinacol ester as a silyl radical precursor. The reaction proceeds under mild conditions via a radical–polar crossover mechanism, affording a variety of aliphatic nitriles in good to high yields with broad functional group tolerance. This protocol can be extended to decyanative deuteration using D2O, enabling the site-selective synthesis of deuterated nitriles. Mechanistic studies suggest that silyl radical addition to the nitrogen atom of the cyano group triggers decyanation through an imidoyl radical intermediate.