Prototropic isomerization of dihydropyridazinecarboxylic and dihydropyridazinedicarboxylic acid esters
- 69 Downloads
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°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 β-aminoacrylate fragment.
Unable to display preview. Download preview PDF.
- 3.Schmidt, M.W., Baldridge, K.K., Boatz, J.A., Elbert, S.T., Gordon, M.S., Jensen, J.J., Koseki, S., Matsunaga, N., Nguyen, K.A., Su, S., Windus, T.L., Dupuis, M., and Montgomery, J.A., J. Comput. Chem., 1993, vol. 14, p. 1347; Nemukhin, A.V., Grigorenko, B.L., and Granovskii, A.A., Vestn. Mosk. Univ., Khim., 2004, vol. 45, p. 75.CrossRefGoogle Scholar
- 4.MarvinBeans 5.3.7; http://www.chemaxon.com.
- 6.Vasin, V.A. and Razin, V.V., Synlett, 2001, p. 658.Google Scholar
- 7.Breslow, R. and Battiste, M., Chem. Ind., 1958, p. 1143.Google Scholar