Synthesis and reactions of 1-(5-azido-5-deoxy-3-O-p toluenesulfonyl-β-d-xylofuranosyl) derivatives of 5-alkyl- and 5-halo-pyrimidines

Chemical syntheses of 1-(2-O-acetyl-5-azido-5-deoxy-3-O-p-toluenesulfonyl-β-d-xylofuranosyl)-5-iodo-, -5-fluoro-, and -5-trifluoromethyl-uracil nucleosides (11–13) as well as the thymine analogue 10 were performed from a sugar precursor and the corresponding uracil bases. Partial deblocking of 10–13 gave the 5′-azido-5′-deoxynucleosides 14–17. The 3′,5′-diazido-3′,5′-dideoxyribonucleosides were obtained in the same way. The 2′,3′-anhydro analogue 20 was prepared by treatment of 10 with potassium carbonate in methanol or a basic ion-exchange resin. Reaction of 10 with azide or methanethiolate ions gave 2′-azido- and 2′-thiomethyl-ribonucleosides, respectively. Similarly, 13 gave a 2′-thiomethylribonucleoside on treatment with methanethiolate ion. Treatment of 16 with phenoxythiocarbonyl chloride in basic medium afforded a 2′,3′-anhydro derivative and not the expected ester.