Selective hydrolysis of phosphorus(V) compounds to form organophosphorus monoacids

An azide and transition metal-free method for the synthesis of elusive phosphonic, phosphinic, and phosphoric monoacids has been developed. Inert pentavalent P(V)-compounds (phosphonate, phosphinate, and phosphate) are activated by triflate anhydride (Tf₂O)/pyridine system to form a highly reactive phosphoryl pyridinium intermediate that undergoes nucleophilic substitution with H₂O to selectively deprotect one alkoxy group and form organophosphorus monoacids.