Synthesis of 6-chloro-9-(6′-deoxy-3′-C-methyl-2′,3′,4′-tri-O-methyl- β-D-allopyranosyl)purine: a branched-chain sugar nucleoside

The preparation of 6-deoxy-3-C-methyl-2,3,4-tri-O-metliyl-D-allopyranose (7), a branclied-chain sugar with the same constitution as nogalose from the antibiotic nogalamycin, is described. Condensation of the 1-O-acetyl derivative 8with 6-chloropurine by the fusion method gave 6-chloro-9-(6′-deoxy-3′-C-methyl-2′,3′,4′-tri-O-methyl-β-D-allopyranosyl)purine (9), which to our knowledge is the first synthetic, purine nucleoside containing a branched-chain sugar with a pyranose ring.