Addition reactions of heterocyclic compounds. Part XLII the mechanism of the thermal rearrangement of tetramethyl 7,9-dimethyl-9aH-quinolizine-1,2,3,4-tetracarboxylate to the 4H-isomer

Abstract

The activation energy and entropy for the rearrangement of tetramethyl 7,9-dimethyl-9aH-quinolizine-1,2,3,4-tetracarboxylate to the 4H-isomer, the large isotope effect observed on replacing the moving hydrogen atom by deuterium, and the lack of exchange of this hydrogen with [²H]ethanol in the rearrangement, indicate that an intramolecular shift occurs.