Heterocyclic betaines. Aza analogs of sesquifulvalene. 2. Azolium azolate inner salts: synthesis, reactivity, and structure of a 1:1 adduct with dimethyl acetylenedicarboxylate
摘要:
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 toward 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.