Improved synthesis and antitumor activity of 1-deazaadenosine

A more convenient synthetic route to 1-deazaadenosine (1) by reduction of the new nucleoside 7-nitro-3-beta-D-ribofuranosyl-3H-imidazo[4,5-b]pyridine (6) is reported. Compound 6 was obtained by reaction of 7-nitroimidazo-[4,5-b]pyridine with 1,2,3,5-tetra-O-acetyl-beta-D-ribofuranose in the presence of stannic chloride followed by treatment with methanolic ammonia. 1-Deazaadenosine (1) showed good activity in vitro as inhibitor of HeLa, KB, P388, and L1210 leukemia cell line growth, with ID50 values ranging from 0.34 microM (KB) to 1.8 microM (P388). The nitro derivative 6 demonstrated moderate activity against the same cell lines.