title: Imidazol-2-and-4-ylidene by decarboxylation. Studies on the cross-conjugated mesomeric betaine-alkaloid norzooanemonine and its pseudo-cross-conjugated isomer.
abstract: 1,3-Dimethylimidazolium-2-carboxylate and -4-carboxylate (norzooanemonine), which belong to two distinct classes of heterocyclic mesomeric betaines, undergo thermal decarboxylations to the N-heterocyclic carbenes imidazol-2-ylidene and imidazol-4-ylidene, respectively. These carbenes can be detected by ESI mass spectrometry and can be trapped by isocyanates to imidazolium-amidates, the structure of which was proved by independent syntheses. We performed calculations to characterize the different types of conjugation in the imidazolium-carboxylates.
authors.affiliation: Clausthal University of Technology, Institute of Organic Chemistry, Leibnizstrasse 6, D-38678, Clausthal-Zellerfeld, Germany. schmidt@ioc.tu-clausthal.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Schmidt
authors.forename: Ariane
authors.initials: A
authors.lastname: Beutler
authors.forename: Marcel
authors.initials: M
authors.lastname: Albrecht
authors.forename: Bohdan
authors.initials: B
authors.lastname: Snovydovych
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Ramírez
mesh_terms: D000470:Alkaloids / Q000737:chemistry*; D001622:Betaine / Q000031:analogs & derivatives* / Q000737:chemistry*; D003653:Decarboxylation; D007093:Imidazoles / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D055672:Static Electricity; D013237:Stereoisomerism
chemical_list: D000470:Alkaloids; D007093:Imidazoles; C527568:norzooanemonine; D001622:Betaine