Synthesis of 3,6-anhydro sugars from cyclic sulfites and sulfates and their applications in the preparation of bicyclonucleoside analogues of ddC andddA

Cyclic sulfates 21-23 and sulfite 27 derived from glucofuranose lead to the 3,6-anhydrosugar 28 in excellent yields when treated with sodium sulfite o r in basic media. When treated with sodium sulfite, the 3-deoxy derivative 24 fails to give the intramolecular cyclization which leads to the anhydros ugars. Instead it gives the disulfonate derivative 26. 28 was used as start ing material to prepare bicyclonucleosides 43 and 46, which are analogues o f the anti-HIV agents ddC and ddA. (C) 1999 Elsevier Science Ltd. All right s reserved.