aqueous solution provides sum of some of the proton-proton coupling constants. This limitation precludes the determination of the pseudorotational parameters of the sugar ring. Selective deuteration alleviates this problem. The synthesis of 2′-deutero and 3′-deutero- AZT have been described for the first time starting from D-xylose and β-thymidine respectively. NMR study of these analogues in aqueous