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

A substantial improvement in the challenging photocatalytic arylation of white phosphorus (P 4 ) with aryl chlorides and bromides is reported. Using the readily accessible deazaflavin‐based photocatalyst o ‐Me‐dFl, valuable triarylphosphines (PAr 3 ) and tetraarylphosphonium salts ([PAr 4 ]X, X = Br, Cl) are synthesized from P 4 under near UV‐LED (365 nm) irradiation in up to 87% combined yield with drastically reduced reaction times compared to previous protocols. 31 P nuclear magnetic resonance spectroscopic monitoring studies and density functional theory calculations provide insights into the reaction pathway. The results represent an important step toward more atom‐efficient and economical photocatalytic P 4 functionalization reactions.