SYNTHESIS OF -2,3-DIDEOXY-BETA-D-RIBO-HEXOFURANOSYL)PYRIMIDINE, ,3-DIDEOXY-BETA-D-ERYTHRO-HEXOFURANOSYL)PYRIMIDINE AND DEOXY-BETA-D-ERYTHRO-HEX-2-ENOFURANOSYL)PYRIMIDINE NUCLEOSIDES

Azido-2,3-dideoxy-beta-D-ribo-hexofuranosyl)uracil (XXII) and 3-dideox y-beta-D-erythro-hex-2-enofuranosyl)uracil (VIII) were prepared starti ng from l-3,5,6-tri-O-benzoyl-beta-D-glucofuranosyl)uracil (I) by a pr ocedure described previously for thymine analogs. 1-(2,3-Dideoxy-beta- D-erythro-hexofuranosyl)uracil (XIII) was obtained by catalytic hydrog enation of 3-dideoxy-beta-D-erythro-hex-2-enofuranosyl)uracil (VII) an d subsequent methanolysis. Reaction of dibenzoyl derivative VII, yl-2, 3-dideoxy-beta-D-erythro-hexofuranosyl)uracil (XII) and the diacetate prepared by acetylation of azido derivative XXII with Lawesson's reage nt, followed by methanolysis, afforded xy-beta-D-erythro-hex-2-enofura nosyl)-4-thiouracil (X), i-deoxy-beta-D-erythro-hexofuranosyl)-4-thiou racil (XV) and ,3-dideoxy-beta-D-ribo-hexofuranosyl)-4-thiouracil (XXI II), respectively. Heating of thio derivatives X, XV and XXIII with me thanolic ammonia at 100-degrees-C gave dideoxy-beta-D-erythro-hex-2-en ofuranosyl)cytosine (XI), (2,3-dideoxy-beta-D-erythro-hexofuranosyl)cy tosine (XVI) and ido-2,3-dideoxy-beta-D-ribo-hexofuranosyl)cytosine (X XIV).