1,3-Dipolar cycloaddition of cyanopyridines to heterocyclic N-imines: experimental and theoretical study

Microwave-Mediated, Catalyst-Free Synthesis of 1,2,4-Triazolo[1,5-a]pyridines from Enaminonitriles

“…This cascade reaction proceeds via C-N coupling, followed by Boulton–Kartritzky rearrangement [ 27 ]. In 2022, Cao and coworkers reported the reaction of N -iminoisoquinolinium ylides with dioxazolone as an acyl nitrile source in the presence of copper acetate, providing 1,2,4-triazolo[1,5- a ]pyridines via C-H amidation and cyclization [ 28 ], and so on [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ]. Despite the efficiency of these methods in several aspects, there are still some limitations, including the use of solvent in large quantities, longer reaction times, multistep processes, and, in several cases, the requirement for either metal or external catalysts, which will come out as chemical hazards.…”

Synthesis of Tetrazines from N-Allenylpyrrole-2-carbaldehydes and pH-Controlled Reversible Fragmentation

“…17−21 This process could proceed in the basic medium, as was described by Tsuchiya. 17 In a recent work, 22 the dimer of N-aminopyridinium salt was isolated and characterized during the synthesis of triazolazines. Also, heteroanthracene structures (with six nitrogen atoms) were obtained by dimerization of quinoxalinone oxime under the action of aqueous cobalt(II) chloride.…”