An improved procedure is described for the efficient and high-yield (76-91%) synthesis of nucleoside diphosphate sugars from the readily available nucleoside 5'-monophosphomorpholidate and sugar l-phosphate in the presence of VI-tetrazole, Comparative kinetic investigations by means of P-31 NMR spectroscopy with different additives (1,a,4-triazole, acetic acid, N-hydroxysuccinimide, 4-(dimethylamino)pyridine hydrochloride, perchloric acid) and mass spectrometric analysis suggest that tetrazole acts as an acid and as a nucleophilic catalyst in the pyrophosphate bond formation.
