Photocatalytic Difunctionalization of Vinyl Ureas by Radical Addition Polar Truce–Smiles Rearrangement Cascades

We report tandem alkyl-arylations and phosphonyl-arylations of vinyl ureas by way of a photocatalytic radical-polar crossover mechanism. Addition of photoredox-generated radicals to the alkene forms a new C-C or C-P bond and generates a product radical adjacent to the urea function. Reductive termination of the photocatalytic cycle generates an anion that undergoes a polar Truce-Smiles rearrangement, forming a C-C bond. The reaction is successful with a range of α-fluorinated alkyl sodium sulfinate salts and diarylphosphine oxides as radical precursors, and the conformationally accelerated Truce-Smiles rearrangement is not restricted by the electronic nature of the migrating aromatic ring. Formally the reaction constitutes an α,β-difuctionalisation of a carbon-carbon double bond, and proceeds under mild conditions with visible light and a readily available organic photocatalyst. The products are α,α-diaryl alkylureas typically functionalized with F or P substituents that may be readily converted into α,α-diaryl alkylamines.