Deazapurine derivatives. IX: Synthesis of (7‐substituted)‐1‐, 2‐ and 3‐β‐D‐ribofuranosyl‐<i>vic</i>‐triazolo [4,5‐<i>b</i>]pyridines. 1‐Deaza‐8‐aza‐adenosine and related compounds

Abstract

Abstract The direct condensation of 7‐chloro‐ vic ‐triazolo[4,5‐ b ]pyridine (I) with 2,3,5‐tri‐ O ‐benzoylribofuranosyl chloride (III) in nitromethane containing potassium cyanide, afforded two isomeric blocked nucleosides. Debenzoylation of these products gave the ribosides 7‐chloro‐3‐β‐D‐ribofuranosyl‐ vic ‐triazolo[4,5‐ b ]‐pyridine (VI) and its 2‐ribosylated isomer VII. From the reaction of the chloromercuri derivative of vic ‐triazolo[4.5‐ b ]pyridine (X) with III in boiling toluene, followed by subsequent debenzoylation of the reaction products, three isomeric ribosides were obtained: 1‐, 2‐ and 3‐β‐D‐ribofuranosyl‐ vic ‐triazolo[4,5‐ b ]‐pyridine (XVI, XV and XIV). The position of attachment of the sugar moiety to the vic ‐triazolo[4.5‐ b ]pyridine ring system and the assignment of anomeric configuration for all nucleosides reported, are discussed. A number of 7‐substituted 3‐β‐D‐ribofuranosyl‐ vic ‐triazolo[4,5‐ b ]pyridines ‐ including 1‐deaza‐8‐aza‐adenosine (XXVI) ‐ was obtained by replacement of the chloro group of VI.