Synthesis of 5-amino-1-(5-deoxy-beta-D-ribofuranosyl)imidazole-4-carboxamide and related 5'-deoxyimidazole ribonucleosides.

5-Amino-1-(beta-D-ribofuranosyl)imidazole-4-carboxamide (1, AICA ribonucleoside) was converted in two steps to 5-amino-1-(5-deoxy-5-iodo-2,3-O-isopropylidene-beta-D-ribofuranosyl)imidazole-4-carboxamide (3) which was hydrogenated in the presence of Pd/C to yield 5-amino-1-(5-deoxy-2,3-O-isopropylidene-beta-D-ribofuranosyl)imidazole-4-carboxamide (4). The dehydration of 4 yielded 5-amino-1-(5-deoxy-2,3-O-isopropylidene-beta-D-ribofuranosyl)imidazole-4-carbonitrile (7). The compounds 3, 4, and 7 were deblocked with formic acid to furnish 5-amino-1-(5-deoxy-5-iodo-beta-D-ribofuranosyl)imidazole-4-carboxamide (6). 5-amino-1-(5-deoxy-beta-D-ribofuranosyl)imidazole-4-carboxamide (5), and 5-amino-1-(5-deoxy-beta-D-ribofuranosyl)imidazole-4-carbonitrile (8), respectively. Compound 8 was acetylated and then deaminated to give 1-(2,3-di-O-acetyl-5-deoxy-beta-D-ribofuranosyl)imidazole-4-carbonitrile (11). The compounds 8 and 11 were converted into 5-amino-1-(5-deoxy-beta-D-ribofuranosyl)imidazole-4-thiocarboxamide (9) and 1-(5-deoxy-beta-D-ribofuranosyl)imidazole-4-thiocarboxamide (12), respectively. The synthesis of 1-(5-deoxy-beta-D-ribofuranosyl)imidazole-4-carboxamide (13) was achieved for the first time by the treatment of 11 with hydrogen peroxide in the presence of ammonium hydroxide. The compounds were tested for antibacterial, antifungal, and antiviral activity, with 5 and 6 significantly inhibitory to Staphylococcus aureus.