A Novel Method for the Synthesis of Purine Nucleosides using Friedel-Crafts Catalysts

9-β-D-Ribofuranosyladenine was synthesized by condensation of N6-octanoyladenine (I) with 1-O-acetyl-2, 3, 5-tri-O-benzoyl-β-D-ribofuranose (II) or 1, 2, 3, 5-tetra-O-acetyl-β-D-ribofuranose (III) in sym-dichloroethane or chlorobenzene in the presence of Friedel-Crafts catalysts followed by hydrolysis of the acyl groups. By this procedure the formation of the corresponding anomer was not observed Similarly, 9-β-D-ribopyranosyladenine was synthesized from I and 1, 2, 3, 4-tetra-O-acetyl-β-D-ribopyranose, and 9-β-D-ribofuranosylguanine in high yield from N2-palmitoylguanine and III.