Activation of Cyanate Anions by Phosphine Radical Cations Enables Formal Hydrocarbamoylation of Alkenes

Catalytic methods that enable functionalization of alkenes with radical intermediates generated from common feedstock chemicals are valuable in synthetic chemistry. In this study, we disclose a photocatalytic formal hydrocarbamoylation strategy for preparation of N-acyl iminophosphorane products from activated alkenes through isocyanate-derived phosphoranyl radicals. Mechanistic investigations suggest generation of the phosphoranyl radical by addition of a cyanate anion to a phosphine radical cation and provide support for its reactivity through the isocyanate moiety. This redox-neutral method enables hydrofunctionalization of diverse alkenylarene and electron-deficient alkene substrates containing sensitive groups such as epoxide, unactivated alkene, amine, or electron-rich and electron-deficient heterocycles. The synthetic versatility of the N-acyl iminophosphorane functionality is demonstrated through one-step conversion to other valuable nitrogen-containing functional groups.