Synthesis and Characterization of Dialkyl Esters of 1,2,4,5-Tetrazine-3,6-dicarboxylic Acid

Abstract

Synthesis and characterization of a series of dialkyl esters of 1,2,4,5-tetrazine-3,6-dicarboxylic acid are reported. These compounds were prepared by a two-stage synthesis: re-esterification of dimethyl 1,4-dihydro-1,2,4,5-tetrazine-3,6-dicarboxylate in the presence of aluminium triethoxide and subsequent dehydrogenation of dialkyl 1,4-dihydro-1,2,4,5-tetrazine-3,6-dicarboxylates. The structures of the prepared compounds were confirmed by NMR and mass spectra.

Synthesis of esters and amides of 1,4-dihydro-1,2,4,5-tetrazine-3,6-dicarboxylic acid

“…Recently, Almonasy's group has established the transesterification of dimethyl 1,4-dihydro-1,2,4,5-tetrazine-3,6-dicarboxylate in the presence of aluminium triethoxide, but their products limited to unbranched symmetric dialkyl esters of 1,4-dihydro-1,2,4,5-tetrazine-3,6-dicarboxylic acid. 10 Amidation was also developed to obtain the 1,4-dihydro-1,2,4,5-tetrazine-3,6-dicarboxamide of alkyl amines with good to excellent yields by heating in ethanol solution. However, the reaction proceeded with difficulty with tertbutylamine or aniline, probably due to steric hindrance or the low nucleophilicity of the amines.…”