Preparation and Cycloaddition Reactions of Novel Heterocyclic Mesomeric Betaines

Abstract The heterocyclic mesomeric betaines 6a – c reacted with dimethyl acetylenedicarboxylate and ethyl propiolate giving the 1,3-dipolar cycloaddition products 7a – c and 8a – c , respectively. With esters of maleic, fumaric, acrylic and methacrylic acids, mesomeric betaines 6a and 6b gave substituted tetralone derivatives.