General method for the synthesis of 2′-azido-2′,3′-dideoxynucleosides by the use of [1,2]-hydride shift and β-elimination reactions

The title nucleosides (16U, C, G and H) were synthesized from pyrimidine and purine ribonucleosides in about 30% overall yield in 6 steps via key intermediates, protected 3′-deoxy-‘arabino’-nucleosides, which were obtained by deoxygenative [1,2]-hydride shift and β-elimination reactions of sulfonylated ribo-counterparts. Xanthine analogues (9X and 16X) were prepared from the corresponding guanine nucleosides. The unprotected 3′-deoxy-‘arabino’-nucleosides (9U,C,A,G,H,X) and their azido nucleosides 16 did not show any significant activity against either HIV in vitro or P388 leukaemia in mice.