2007

Imidazole derivativesR 0190 Substrate-Controlled and Site-Selective [3 + 2] Cycloadditions of N-Heterocyclic

Carbene Derived Ambident Dipoles. — The highly site-selective 1,3-dipolar cy-cloaddition of 2-aryl thiocarbamoyl benzimidazolium and imidazolium inner salts with different alkynes and alkenes are investigated. The dipoles act predominantly as C—C—S systems in reactions with alkynes bearing two electron-withdrawing groups such as compounds (II). When treated with alkynes and alkenes substituted with one electron-withdrawing group, they behave as a C—C—N 1,3-dipolar compound. — (CHENG, Y.; LIU, M.-F.; FANG*, D.-C.; LEI, X.-M.; Chem. Eur. J. 13 (2007) 15, 4282-4292; Dep. Chem., Beijing Norm. Univ., Beijing 100875, Peop. Rep. China; Eng.) — Bartels

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