QUATERNARISATION DE L'ATOME D'AZOTE DE SYSTEMES TAUTOMERES DE LA SERIE DES OXO-4 THIAZOLES. CYCLOADDITIONS DIPOLAIRES 1,3 DES THIAZOLES MESOIONIQUES FORMES IN SITU

Article abstract of DOI:10.1016/S0040-4020(01)83124-0

4-Hydroxythiazoles and N-acylimino 4-thiazolidinones show similar tautomeric behaviour to azlactones.However, the mechanism of their reaction with dimethylacetylenedicarboxylate or with ethyl vinyl ether differs fundamentally.In the thiazole series, the first step is the quaternization of the nitrogen atom.The mesoionic thiazole intermediate is then trapped by a second molecule of the dipolarophile.