Photocatalytic Arylation of P4 and PH3: Reaction Development Through Mechanistic Insight

Abstract Detailed 31 P{ 1 H} NMR spectroscopic investigations provide deeper insight into the complex, multi‐step mechanisms involved in the recently reported photocatalytic arylation of white phosphorus (P 4 ). Specifically, these studies have identified a number of previously unrecognized side products, which arise from an unexpected non‐innocent behavior of the commonly employed terminal reductant Et 3 N. The different rate of formation of these products explains discrepancies in the performance of the two most effective catalysts, [Ir(dtbbpy)(ppy) 2 ][PF 6 ] (dtbbpy=4,4′‐di‐ tert ‐butyl‐2,2′‐bipyridine) and 3DPAFIPN. Inspired by the observation of PH 3 as a minor intermediate, we have developed the first catalytic procedure for the arylation of this key industrial compound. Similar to P 4 arylation, this method affords valuable triarylphosphines or tetraarylphosphonium salts depending on the steric profile of the aryl substituents.