Collect. Czech. Chem. Commun. 1981, 46, 2104-2109

Ketimine-enamine tautomerism of 2-ethoxycarbonylmethylene-4-methyl-3-oxo-1,2,3,4-tetrahydroquinoxaline: A kinetic study

Jaromír Toman, Vojeslav Štěrba and Jiří Klicnar

Department of Organic Chemistry, Institute of Chemical Technology, 523 10 Pardubice


Tautomerism of the title compound in methanol in the presence of buffers is subject to general acid and base catalysis. The rate-limiting step of the acid-catalyzed reaction consists in addition of the proton to the methine carbon atom of the enamine form, whereas that of the base catalyzed reaction consists in protonation of the formed conjugated base of the enamine. Solvent effects on the equilibrium constant of the isomerization have been measured.