Phosphoramidates phosphoromorpholidates

The chemical synthesis of uridine 5-(a-D-glucopyranosyl pyrophosphate) has been effected by condensing a-n-glucopyranosyl phosphate with uridine 5-phosphate in the presence of dicyclohexylcarbodiimide. The yield of glycosyl nucleotide in this reaction is very low, primarily because dicyclohexylcarbodiimide promotes the formation of n-glucose cyclic 1,2-phosphate in preference to the formation of the pyrophosphate bond. In an improved synthetic method, the nucleotide is first converted to a phosphoramidate (5) or phosphoromorpholidate (6), by condensation in the presence of dicyclohexylcarbodiimide with ammonia or morpholine, respectively. 

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