Synthesis of ribonucleosides of 4(5)‐cyano‐5(4)‐methylimidazole and related 4‐substituted‐5‐methylimidazole ribosides

4-Cyano-1-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)-5-methylimidazole (4) and its corresponding 5-cyano-4-methyl substituted isomer (5) have been obtained by ribosylation of 4(5)-cyano-5(4)-methylimidazole (3) via the mercuric cyanide method or by ribosylation of the trimethylsilyl derivative of 3. Treatment of 4 with methanolic ammonia, ammonium chloride in liquid ammonia and potassium hydrosulfide provided 4-cyano-1-β-D-ribofuranosyl-5-methylimidazole (6), 1-β-D-ribofuranosyl-5-methylimidazole-4-carboxamide (2) and 1-β-D-ribofuranosyl-5-methylimidazole-4-thiocarboxamide (11) respectively. Reaction of 6 with hydroxylamine afforded the corresponding 4-carboxamidoxime substituted nucleoside (13) which on catalytic reduction in the presence of ammonium chloride, was transformed into 1-β-D-ribofuranosyl-5-methylimidazole-4-carboxamidine (14) as hydrochloride salt