The diastereoselective synthesis of “pre-activated” analogues of cyclophosphamide in the 3- [bis (2-chloroethyl) amino]-2-aza-4, 9-dioxa-3-phosphabicyclo (4.3. 0) nonane 3-oxide series in described, using either the phosphorylation of an azidoalcohol followed by a reductive cyclisation or the phosphorylation of an acetal alcohol followed by an unprecedent direct Lewis acid catalyzed intramolecular substitution.
