Some reactions of 3,6‐disubstituted‐s‐tetrazines; A new synthesis of the 1,2,4‐triazine ring system

Abstract

The synthesis of variously substituted pyridazines by 1,4‐cycloaddition of cyclic enol ethers, esters, and some electron‐rich acetylenes is described. Extension of the scheme to include some imino‐ethers as dienophiles resulted in the synthesis of 1,2,4‐triazine derivatives.

Synthesis and Characterization of Bis-azo 1,2,4,5-Tetrazine Dyestuff

“…As a result of the large range of applications of tetrazine-based products, the inclusion of a heterocyclic tetrazine moiety in molecular structures of different compounds affords such materials new significant properties [1,2]. Symmetrical tetrazine-based materials are a famous group of aromatic heterocyclics that have been applied in a diversity of research areas, such as anti-tumors, metallosupramolecular self-assembly, insecticides, electrochemical materials, fluorescent products, electroactive materials, bio-orthogonal label and cell sensing [3][4][5][6][7][8][9]. Tetrazines can be considered as one of the highest electron deficient aromatic compounds.…”

Heterocyclic N-oxides as synthetic intermediates. 5. Synthesis of 5-aminopyridazine 1-oxides

“…In continuation of our interest in this area, we now have investigated the cycloaddition of 1 with ynamines (7) very mild conditions an exothermic reaction accompanied by the evolution of carbon dioxide produced pyridazine oxides (8) in high yields (Table I). This transformation is analogous to the Diels-Alder reaction of -pyrones with acetylenes6 and occurs in a highly regioselective manner, since the isomeric pyridazine oxide (9) was not detected in any case ( NMR analysis).…”