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.