Studies on imidazole derivatives and related compounds. 4. Synthesis of O‐glycosides of 4‐carbamoylimidazolium‐5‐olate

Abstract

AbstractRibosylation of trimethylsilyl derivative of 1‐(4‐nitrobenzyl)‐5‐carbamoylimidazolium‐4‐olate (5) with 1,2,3,5‐tetra‐O‐acetyl‐β‐D‐ribofuranose in the presence of stannic chloride and trimethylsilyl trifluoromethanesulfonate afforded no 5‐O‐glycosides but N‐1 ribosylated compound (6). However, 5‐O‐riboside (7a) and its orthoamide derivative (8) were given by glycosylation of tri‐n‐butylstannyl derivative of 5 with 2,3,5‐tri‐O‐acetyl‐β‐D‐ribofuranosyl chloride in the presence of silver trifluoromethanesulfonate. This procedure was successfully applied to other sugars and 5‐O‐glucuronide (11), a possible metabolite of 1 in vivo, was obtained as one of the 5‐O‐glycoside derivatives.