Phosphorus and its compounds are a cornerstone of biological life, as well as finding applications in material science, for example, as flame retardants, battery electrolytes or catalysts. In most applications, phosphorus-containing fine chemicals are in the naturally occurring and most stable oxidation state +V of the element; however, syntheses to these compounds from primary PV sources rely on an energy-consuming and wasteful redox detour via elemental white phosphorus (P4) and its subsequent (oxy)chlorination to PCl3, PCl5 and POCl3. Here we report an approach using trifluoromethanesulfonic anhydride (Tf2O) and pyridine to directly cleave P–O bonds in ubiquitous PV sources to form the versatile PO2+ phosphorylation agent (pyridine)2PO2[OTf] (1[OTf]), whose preparation and mechanism of formation is discussed. Harnessing its reactivity towards various nucleophiles such as amines, alcohols and pseudohalogenides, 1[OTf] then provides redox-neutral access to a range of value-added PV chemicals downstream of low-cost phosphoric acid or other phosphate sources. [Figure not available: see fulltext.].
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|Published - Oct 2023