REACTIONS DE CYCLOADDITION DIPOLAIRE-1,3 DES THIAZOLONES ET DES SELENAZOLONES MESOIONIQUES AVEC L'ACETYLENE DICARBOXYLATE DE METHYLE-II

Article abstract of DOI:10.1016/0040-4020(82)85160-0

Mesoionic thyazolones and selenazolones react with dimethyl acetylene dicarboxylate to give thiophenes or pyridones.We show that the reactivity of the mesoionic thiazolones towards dimethyl acetylene dicarboxylate may be explanied by second order perturbation theory, limited to frontier orbitals.The influence of the temperature and of the nature of the substituants on the evolution of the primary cycloadduct can be explained by competition between a retro Diels-Alder rection giving a thiophene and a desulfurisation or a deselenurisation giving a pyridone.