Cyclophosphamides from aminosugars and aminonucleosides

Condensation of bis‐(2‐chloroethyl)phosphoramidic dichloride with 3′‐amino‐3′‐deoxy‐ N , N ‐dimethyladenosine afforded the 2′,3′‐cyclicphosphorodiamidate (III). By an improved synthesis, methyl 3‐amino‐3‐deoxy‐β‐D‐ribofuranoside was obtained as a model compound for conversion to the analogous 2,3‐cyclicphosphorodiamidate (XII). Existence of the latter as two diastereomers due to phosphorus asymmetry was shown by nmr analysis, using comparison with the 5‐( O ‐ p ‐nitrobenzoate) (XIII) as a basis for assignments.