Synthesis of new conjugated mesomeric betaines from alkoxycarbonylazinium salts

A new series of conjugated mesomeric betaines have been synthesized from the reaction of various aminoheterocycles with 2-methylthio-4-oxo-3-phenylpyrido[2,1-φ][1,2,4]triazinium iodide, itself prepared from 2-ethoxycarbonylpyridinium N-aminide. Some of the heterobetaines and salts obtained have been studied by 1H-NMR, and their structures have been confirmed by X-ray analysis. The crystal structures reveal unexpected complementary stabilizing interactions between some betaines and their salts.We wish to express our thanks to the Comisió Interdepartamental de Reçerca i Innovació Tecnológica (CIRIT) for financial support (Project QFN94-4619) and to the Ministerio de Educación y Ciencia for a grant to one of us (JVM)