Photocatalytic Decyanation of Arylacetonitriles Enabled by Diphenylboryl Radicals via Spin Delocalization and α-Fragmentation

Aliphatic nitriles are abundant and versatile feedstocks used for building complex molecular structures via α functionalization, involving the exploitation of the inherent properties of their cyano (CN) group. Streamlined access to diverse hydrocarbon frameworks can be achieved by combining CN-assisted functionalization with subsequent removal of the CN group, yet direct decyanation remains challenging because of the high C–CN bond dissociation energy and the strongly negative reduction potential. In this study, we developed a photocatalytic strategy that leveraged the unique reactivity of diphenylboryl radicals to enable the decyanation of unactivated aliphatic nitriles. Mechanistically distinct from conventional approaches, this reaction proceeded via spin-delocalized N-borylimidoyl radicals that are generated by the coordination of nitriles to the electron-deficient diphenylboryl radical. These radicals underwent α-fragmentation to cleave the C(sp³)–CN bond, affording a C-centered radical. This platform can be extended also to the deisocyanation, providing an indirect pathway for deamination.