Nucleosides 2: Synthesis and properties of 3,4-diaryl-4,5-dihydro-1-(beta-D-ribofuranosyl)-1,2,4-triazole-5-thiones

3,4-Diaryl-4,5-dihydro-1,2,4-triazole-5-thiones, (1a-c) were silylated to g ive compounds (2a-c) which were condensed with 1-O-acetyl-2,3,5-tri-O-benzo yl-beta-D-ribofuranose (3) in the presence of trimethylsilyl trifluorometha ne sulfonate to afford the corresponding nucleosides 4a-c. Treatment of 4a- c with sodium methoxide in methanol at room temperature afforded the debenz oylated nucleosides 5a-c. The reaction of 5a with acetone in the presence o f p-toluenesulfonic acid gave the 2', 3'-isopropylidene derivative (6a). Ph osphorylation of 6a with phosphoryl chloride and triethylphosphate followed by treatment with barium hydroxide afforded barium 3,4-diphenyl-4,5-dihydr o(beta-D-ribofuranosyl)-1,2,4-triazole-5-thione-5'- monophosphate, which ga ve after lyophilization the free acid (7a).