ENZOTRIAZOL-1-YLOXY)TRIS(DIMETHYLAMINO)PHOSPHONIUM HEXAFLUOROPHOSPHATE-MEDIATED AND (1H-BENZOTRIAZOL-1-YLOXY)TRIPYRROLIDINOPHOSPHONIUM HEXAFLUOROPHOSPHATE-MEDIATED ACTIVATION OF MONOPHOSPHONATE ESTERS - SYNTHESIS OF MIXED PHOSPHONATE DIESTERS, THE REACTIVITY OF THE BENZOTRIAZOLYL PHOSPHONIC ESTERS VS THE REACTIVITY OF THE BENZOTRIAZOLYL CARBOXYLICESTERS

A general method for synthesizing mixed phosphonate diesters from mono esters using (1H-benzotriazol-1-yloxy)tris(dimethylamino) hexafluoroph osphate or (1H-benzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluo rophosphate reagents is described. The reaction proceeded through a be nzotriazolyl ester as shown by comparison with other reagents such as DCC, DCC/DMAP, DCC/1-hydroxybenzotriazole, bromotris(dimethylamino)pho sphonium hexafluorophosphate, or 1H-benzotriazol-1-yl)-N,N,N',N'-tetra methyluronium hexafluorophosphate and by P-31 NMR analysis. This benzo triazolyl phosphonic ester intermediate was more reactive toward alcoh ols than toward amines, contrary to its carboxylic analogue.