Oxyonium phosphobetaines – unusually stable nucleophilic catalyst–phosphate complexes formed from H-phosphonates and N-oxides

Aryl H-phosphonates react with N-oxides to form previously unknown stable zwitterionic oxyonium phosphates comprising an −O–P–O–N+Z atom system. Their structures were confirmed i.e. by X-ray crystal structure analysis, and some mechanisms were proposed for their formation. Stability during storage and reactivity toward nucleophiles points to their possible synthetic applications.