Prototropic isomerization of dihydropyridazinecarboxylic and dihydropyridazinedicarboxylic acid esters
作者:V. V. Razin、M. E. Yakovlev、V. A. Vasin
DOI:10.1134/s1070428012030177
日期:2012.3
3,5-Disubstituted 1,4-dihydropyridazine-4-carboxylic and 4,6-disubstituted 2,5-dihydropyridazine-3,5-dicarboxylic acid esters undergo isomerization into 2,5-dihydropyridazine-4-carboxylate and 1,4-dihydropyridazine-3,5-dicarboxylate derivatives, respectively, by the action of a catalytic amount of a mineral acid or strong base at 20 degrees C. The transformation may be regarded as prototropic rearrangement, and it includes two consecutive 1,2-hydride shifts. The direction of the isomerization is determined by higher thermodynamic stability of the isomer containing a beta-aminoacrylate fragment.