The Base‐Promoted Annulation of 2‐Hydrazinyl Pyridine and CO₂ toward Triazolones

Abstract

A base-promoted annulation of 2-hydrazinyl pyridine and atmospheric pressure of CO 2 has been developed in the presence of silane as reducing reagent, affording a series of triazolones in moderate to excellent yields. CO 2 served as a carbonyl source in this transfomation. Moreover, benzamidrazones also worked well under this procedure. Thus, it represents a green, sustainable and straightforward pathway to access triazolone frameworks.

Synthesis of 3H-1,2,4-Triazol-3-ones via NiCl2-Promoted Cascade Annulation of Hydrazonoyl Chlorides and Sodium Cyanate

“…Considering the urgent demand for environmental friendliness and sustainability, green synthesis has emerged as a mainstream alternative to conventional synthetic pathways. An elegant example was presented by Cheng and coworkers, which realized the facile synthesis of 1,2,4-triazol-3-ones through the metal-free mediated annulation of 2-hydrazinylpyridine or benzamidrazone and atmospheric pressure of CO 2 . In 2021, we disclosed an efficient approach for the construction of 1,2,4-triazol-3-ones via a palladium-catalyzed cascade carbonylative reaction of hydrazonoyl chlorides and NaN 3 with TFBen (benzene-1,3,5-triyltriformate) as a convenient CO surrogate .…”

Recent developments in heterocycle labeling with carbon isotopes

“…However, radiochemistry using [ 11 C]-CO presents unique challenges that are not encountered with regular carbonylation reactions. 12,13 Traditionally, carbonylations are performed at elevated pressures and temperatures, with extended reaction times (typically >12 hours) to improve the poor solubility of CO in common organic solvents and so maximize chemical yields. The short half-life of this isotope precludes such long reaction times and the miniscule amounts of isotopically labeled [ 11 C]-CO result in very low partial pressures, which disfavor its solubility and reactivity.…”

“…The chemistry of carbon monoxide is well established, and metal‐catalyzed carbonylation reactions have been widely explored. However, radiochemistry using [ 11 C]‐CO presents unique challenges that are not encountered with regular carbonylation reactions . Traditionally, carbonylations are performed at elevated pressures and temperatures, with extended reaction times (typically >12 hours) to improve the poor solubility of CO in common organic solvents and so maximize chemical yields.…”

One Step Synthesis, Characterization of Modified Montmorillonite with Hydrothermal-Assist for Triazolone Sustained Release System with pH Sensitivity

“…In this work, montmorillonite K-10 clay (MMT) was surface-modified by sodium dodecyl sulfate (SDS), which is selected as the co-intercalation agent with coupling agent KH-550 explained in terms of the closeness of the SDS length (18.0 Å) in the long-axis direction to the MMT interlayer (14.3 Å), thus promoting the nanoenvironment and compositions of the tuneable interlayer [13] to construct "Hy-MMT" organic modified structure in one step [14]. Triazolone which are widely considered to be antibacterial, anti-inflammatory, antiviral, antitumour and antiasthmatic agents [15] was used as a model drug and loaded via impregnation construct Tri/Hy-MMT sustained release system. A silane coupling agent (KH-550), which could react with both the hydroxyl groups of MMT and coordinated with triazolone with its amino group, was recommended to connect them [16,17].…”