Photocatalytic Strategy for Decyanative Transformations Enabled by Amine-Ligated Boryl Radical

Alkyl nitriles are attractive and useful feedstocks for assembling molecular complexity through α-functionalization by exploiting the inherent electron-withdrawing property and coordination ability of cyano groups. Decyanation after α-functionalization enables the strategic assembly of carbon scaffolds in the field of organic synthetic chemistry. However, there are significant limitations to its application in redox chemistry, where allows the preparation of more high-value compounds through the cleavage of C(sp3)–CN to form carbon-centered radicals. In this study, we demonstrate an amine-ligated boryl-radical-mediated cyano group transfer (CGT) strategy of malononitriles under the photocatalytic conditions. This strategy allows for the cleavage of C(sp3)–CN and the formation of new C(sp3)–D and C(sp3)–C(sp3) through a radical-polar crossover mechanism. The mild reaction conditions employing organic photocatalysts and visible light are amenable to a broad range of structurally complex malononitriles and various functional groups. Computational studies successfully guided switching of the CGT promoters from amine-ligated boryl radicals to silyl radicals, depending on the substrate. Furthermore, the CGT approach was extended to decyanative olefination by merging it with cobalt catalysis, where the potential for retro-hydrocyanation was also revealed.