Studies of Nucleosides and Nucleotides. L. Purine Cyclonucleosides. (14). Synthesis and Properties of Cyclonucleosides derived from 9-D-Xylofuranosyladenine

Abstract

N6-Benzoyladenine (II) and 1, 2, 3, 5-tetraacetyl-D-xylofuranose (I) were condensed by fusion method to obtaine α- and β-D-xylofuranosyladenine (IV). Though the β-nucleoside was obtained in a pure crystalline form, the α-anomer was obtained as crystals containing 27% β-anomer as measured by nuclear magnetic resonance. β-D-Xylofuranosyladenine (IVa) was brominated at 8-position and then derived to 3', 5'-O-isopropylidene derivative (VI). Tosylation of VI at 2'-OH followed by the treatment with 40% aqueous NaSH gave a cyclonucleoside, 8, 2'-anhydro-8-mercapto-3', 5'-O-isopropylidene-β-D-xylofurnaosyladenine (VII). De-sulfurization with Raney nickel and deprotection with acid gave a novel nucleoside, 9-β-(2-deoxy-threo-D-pentofuranosyl) adenine (X). From α-D-xylofuranosyladenine (IVb), bromination at 8-position with brominewater in pH 4 gave a crystalline cyclonucleoside, 8, 2'-anhydro-8-oxy-9-α-D-xylofuranosyladenine (XV). Optical rotatory dispersion spectrum of XV showed a large negative Cotton effect in contrary to the β-cyclonucleoside, which had the positive effect in B-band region.