Abstract
An alternative synthesis of 2', 3', 5'-tri-O-benzoyl-N, N, 3-trimethyladenosine iodide (9a) was attained by the reaction of N, N, 3-trimethyladenine (11a) with 1-O-acetyl-2, 3, 5-tri-O-benzoyl-β-D-ribofuranose (10) in the presence of SnCl4 followed by treatment with NaI. Although 3-benzyl-N, N-dimethyladenine (11c) did not react with under similar conditions, the ribosylation of 3-ethyl-N, N-dimethyladenine (11b) followed by alkaline hydrolysis led to the first synthesis of 5-(ethylamino)-1-β-D-ribofuranosyl-1H-imidazole-4-carboxamide (15b). A more general procedure for the synthesis of 5-(alkylamino)-1-β-D-ribofuranosyl-1H-imidazole-4-carboxamides (15) was developed via a series of reactions : alkylation of N'-benzyloxy-5-formamido-1-β-D-ribofuranosyl-1H-imidazole-4-carboxamidine (12) with alkyl halides in the presence of K2 CO3, catalytic hydrogenolysis, and alkaline hydrolysis. By means of this method, 5-(benzylamino)- (15c) and 5-(isopropylamino)-1-β-D-ribofuranosyl-1H-imidazole-4-carboxamide (15d) were synthesized for the first time.
