Deazaflavin-Catalyzed Arylation of White Phosphorus with Aryl Bromides and Chlorides

We report a substantial improvement in the challenging photocatalytic arylation of white phosphorus (P4) with aryl chlorides and bromides. Using the readily accessible deazaflavin-based photocatalyst o-Me-dFl, valuable triarylphosphines (PAr3) and tetraaryl-phosphonium salts ([PAr4]X, X = Br, Cl) were synthesized from P4 under near UV-LED (365 nm) irradiation in up to 87% combined yield with drastically reduced reaction times compared to previous protocols. 31P NMR spectroscopic monitoring studies and density functional theory calculations provide insights into the reaction pathway. Our results represent an important step toward more atom-efficient and economical photocatalytic P4 functionalization reactions.