Synthesis of certain 1,2,4‐triazole nucleoside derivatives

Abstract

Abstract The syntheses of 3‐amino‐4‐methyl‐1‐(β‐D‐ribofuranosyl)‐1,2,4‐triazolin‐5‐one ( 8a ) and its 2′‐deoxy analog 8b as well as 5‐amino‐2‐methyl‐1‐(β‐D‐ribofuranosyl)‐1,2,4‐triazolin‐3‐one ( 12 ) have been accomplished. Compounds 8a and 8b were synthesized via glycosylation of 3‐bromo‐5‐nitro‐1,2,4‐triazole which was followed by replacement in three steps of the 3‐bromo function to yield 3‐nitro‐1‐(2,3,5‐tri‐ O ‐acetyl‐β‐D‐ribofuranosyl)‐1,2,4‐triazolin‐5‐one ( 4a ) and its 2′‐deoxy analog 4b . Compounds 4a and 4b were methylated at N 2 , hydrogenated and deblocked to give 3‐amino‐4‐methyl‐1‐(β‐D‐ribofuranosyl)‐1,2,4‐triazolin‐5‐one ( 8a ) and the 2′‐deoxy analog 8b . Compound 12 was synthesized by glycosylation of 3‐amino‐1‐methyl‐1,2,4‐triazolin‐5(2 H )‐one ( 10 ). The structures of 8b and 12 were confirmed by single crystal X‐ray diffraction analysis.