Heterocyclic Betaines. Aza Analogues of Sesquifulvalene. 2. Azolium Azolate Inner Salts: Synthesis, Reactivity, and Structure of a 1:1 Adduct with Dimethyl Acetylenedicarboxylate

Article abstract of DOI:10.1021/jo00013a029

Reaction of an activated 2-chloroazole with several N-alkylazoles afforded the N-azolylazolium salts, deprotonation of which results in a series of the title mesomeric betaines 7 and 8.Their reactivity towards electrophiles and dipolarophiles under mild conditions reflects the highly dipolar structures of 7 and 8.The thermal stability and dequaternization reactions of some of their corresponding N-azolylimidazolium and -pyrazolium salts have also been studied.