SYNTHESIS OF DEOXY, DIDEOXY AND DIDEHYDRODIDEOXY ANALOGS OF 9-(BETA-D-HEXOFURANOSYL)ADENINE

Condensation of 1,2-di-O-acetyl-3,5,6-tri-O-benzoyl-D-glucofuranose with N6-benzoyladenine, catalyzed with tin tetrachloride, afforded nucleoside I. Partial deacetylation of I, followed by mesylation, gave 9-(3,5,6-tri-O-benzoyl-2-0-methanesulfonyl-beta-D-glucofuranosyl)adenine (III). 9-(2,5,6-Tri-O-acetyl-3-0-methanesulfonyl-beta-D-glucofuranosyl)-N6-benzoyladenine (IV) was prepared by condensation of 1,2,5,6-tetra-0-acetyl-3-0-methanesulfonyl-D-glucofuranose with N6-benzoyladenine. Reaction of mesyl derivative III with methanolic sodium methoxide and of mesyl derivative IV with methanolic ammonia led to 2',3'-anhydronucleosides V and VI which were acetylated to give the respective 9-(5,6-di-O-acetyl-2,3-anhydro-beta-D-mannofuranosyl)adenine (VII) and 9-(5,6-di-O-acetyl-2,3-anhydro-beta-D-allofuranosyl)adenine (VIII). Epoxy derivative VII was cleaved with bromotrimethylsilane, affording a mixture of 9-(5,6-di-O-acetyl-2-bromo-2-deoxy-beta-D-glucofuranosyl)adenine (Xa) and 9-(5,6-di-O-acetyl-3-bromo-3-deoxy-beta-D-altrofuranosyl)adenine (XIa), epoxy derivative VIII was cleaved analogously to give 9-(5,6-di-O-acetyl-3-bromo-3-deoXy-beta-D-glucofuranosyl)adenine (XIIa). Their dehalogenation with tributylstannane and subsequent deacetylation led to 9-(2-deoxy-beta-D-arabino-hexofuranosyl)adenine (Xc), 9-(3-deoxy-beta-D-arabino-hexofuranosyl)adenine (XIc) and 9-(3-deoxy-beta-D-ribo-hexofuranosyl)adenine (XIIc). 9-(2,5,6-Tri-O-acetyl-3-bromo-3-deoxy-beta-D-glucofuranosyl)adenine (XIId), which was prepared by acetylation of XIIa, on reductive elimination with Cu/Zn couple and subsequent deacetylation gave 9-(2,3-dideoxy-beta-D-erythro-hex-2-enofuranosyl)adenine (XIV). 9-(2,3-Dideoxy-beta-D-erythro-hexofuranosyl)adenine (XVI) was obtained either by catalytic hydrogenation of bromo derivative XIId followed by deacetylation, or by catalytic hydrogenation of didehydro derivative XIV. The synthesized nucleosides were tested for antiviral activity.