Photocatalytic Arylation of P<sub>4</sub> and PH<sub>3</sub>: Reaction Development Through Mechanistic Insight
Robin Rothfelder, Verena Streitferdt, Ulrich Lennert, Jose Cammarata, Daniel J. Scott, Kirsten Zeitler, Ruth M. Gschwind, Robert Wolf
Abstract
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.