Syntheses and Applications of 1,2,3-Triazole-Fused Pyrazines and Pyridazines

Abstract

Pyrazines and pyridazines fused to 1,2,3-triazoles comprise a set of heterocycles obtained through a variety of synthetic routes. Two typical modes of constructing these heterocyclic ring systems are cyclizing a heterocyclic diamine with a nitrite or reacting hydrazine hydrate with dicarbonyl 1,2,3-triazoles. Several unique methods are known, particularly for the synthesis of 1,2,3-triazolo[1,5-a]pyrazines and their benzo-fused quinoxaline and quinoxalinone-containing analogs. Recent applications detail the use of these heterocycles in medicinal chemistry (c-Met inhibition or GABAA modulating activity) as fluorescent probes and as structural units of polymers.

Synthesis of Triazolo[4′,5′:4,5]furo[2,3-c]pyridine via Post Modification of an Unusual Groebke–Blackburn–Bienaymé Multicomponent Reaction

“…Detailed crystallographic data and structural refinement parameters are summarized in Tables S1−S3. (20). To a solution of 2-aminopyridine (100 mg, 1.06 mmol, 1.00 equiv) in anhydrous methanol (3.0 mL), pyridoxal hydrochloride (240.3 mg, 1.17 mmol, 1.10 equiv), HCl/dioxane (50 μL), and 1,1,3,3-tetramethylbutyl isocyanide (203.7 μL, 1.17 mmol, 1.10 equiv) were added at room temperature in a 5 mL screwable microwave glass vial, and the vial was sealed.…”

“…It is noteworthy to mention that the “unusual GBB-MCR” is the first and the only report that generates 2,3-diamine-substituted furo­[2,3- c ]­pyridines. Encouraged by the structural diversity obtained in the products generated via post modification of classic GBB reaction, we envisioned that the 2,3-diamino-furo­[2,3- c ]­pyridines synthesized via unusual GBB-MCR is amenable for 1,2,3-triazole construction to generate a library of tricyclic heterocycles utilizing nitrosonium-mediated diazotization. − …”

Synthesis and reactivity of 5-hydrazino-3-nitro-1,2,4-triazole (HNT): an amphoteric energetic platform

“…Obviously, the vast development of so-called click-chemistry 2 has further increased the popularity of triazoles over the recent decades, mostly 1,2,3-triazoles. 3…”