Scalable Rhodium(III)-Catalyzed Aryl C-H Phosphorylation Enabled by Anodic Oxidation Induced Reductive Elimination

Transition metal catalyzed C-H phosphorylation remains an unsolved challenge. Reported methods are generally limited in scope and require stoichiometric silver salts as oxidants. Reported here is an electrochemically driven Rh-III-catalyzed aryl C-H phosphorylation reaction that proceeds through H-2 evolution, obviating the need for stoichiometric metal oxidants. The method is compatible with a variety of aryl C-H and P-H coupling partners and particularly useful for synthesizing triarylphosphine oxides from diarylphosphine oxides, which are often difficult coupling partners for transition metal catalyzed C-H phosphorylation reactions. Experimental results suggest that the mechanism responsible for the C-P bond formation involves an oxidation-induced reductive elimination process.