New Method for the General Synthesis of [1,2,4]Triazolo[1,5‐a]pyridines

Abstract

[1,2,4]Triazolo [1,5-a]pyridines without substituents on the 2-position have been prepared from 2-aminopyridines by cyclization of N-(pyrid-2-yl)formamidoximes with trifluoroacetic anhydride. Triazoles substituted at any position on the pyri-

Solid‐Phase N‐Electrophilic Amination of 2‐Aminopyridines: Preparation of 2‐Substituted‐[1,2,4]triazolo[1,5‐a]pyridine Derivatives

“…Formation of mesitylenesulfonic acid (MSA) (6) (Figure 1) as the byproduct of the reaction was the main impurity detected (8 -70%), the removal of which was not possible even after exhaustive washing of the resins. The quantity of MSA (6) formed depended on the solvent used due to decomposition of the excess of MSH (5).…”

“…Furthermore, if this N-electrophilic amination is carried out on 2-aminopyridines/quinolines the resulting compounds are appropriate intermediates for the preparation of 1,2,4-triazolo derivates [6]. To the best of our knowledge and despite the potential interest in combinatorial chemistry, electrophilic-N-amination of supported pyridines [7] has not been published to date, and the solid-phase synthesis of 1,2,4-triazolopyridines [8] does not use this methodology.…”

Synthesis, radiolabeling and evaluation of novel amine guanidine derivatives as potential positron emission tomography tracers for the ion channel of the N-methyl-d-aspartate receptor

“…The N-methyl-N-(pyridinyl)cyanamides 6aec were synthesized by a three step procedure adapted from Stanovnik et al [26] and Huntsman et al [27]. First, the formamide oximes (5aec) were obtained by a two step reaction from the aminopyridines 4aec with N,N-dimethylformamide dimethyl acetal (DMFeDMA) in 2-propanol, followed by treatment with hydroxylamine hydrochloride (NH 2 OH$HCl) in 52e71% yield.…”

“…HPLC system A: purity 97.5%, rt ¼ 5.03 min.4.2.27. 2,2,2-Trifluoro-N-(2-fluoroethyl)-N-(3-(Nmethylcyanamido)phenyl)acetamide(27) …”

Synthesis of N‐Bridged 6,8‐Dinitrotriazolo[1,5‐a]pyridines

“…The first group (a) include oxidation or sometimes dehydration of pyridylamidines and their derivatives . Route (b) deals with condensation of 1,2‐diaminopyridines with carboxylic acid derivatives,, while route (c) represents the cycloaddition of pyridinium N‐imines with nitriles ,.…”