Fiebig, Anja

[["dc.bibliographiccitation.firstpage","4100"],["dc.bibliographiccitation.issue","12"],["dc.bibliographiccitation.journal","The Journal of Organic Chemistry"],["dc.bibliographiccitation.lastpage","4114"],["dc.bibliographiccitation.volume","67"],["dc.contributor.author","Kozhushkov, S."],["dc.contributor.author","Spath, T."],["dc.contributor.author","Fiebig, T."],["dc.contributor.author","Galland, B."],["dc.contributor.author","Ruasse, M. F."],["dc.contributor.author","Xavier, P."],["dc.contributor.author","Apeloig, Y."],["dc.contributor.author","de Meijere, Armin"],["dc.date.accessioned","2018-11-07T10:25:47Z"],["dc.date.available","2018-11-07T10:25:47Z"],["dc.date.issued","2002"],["dc.description.abstract","The bromine additions to methylenecyclopropane (1), bicyclopropylidene (2), and spirocyclopropanated methylenecyclopropanes and bicyclopropylidenes 3-6 in methanol at 25 degreesC proceed essentially with the same rate as those to the corresponding oligomethyl-substituted ethylenes. An increasing number of spiroannelated three-membered rings enhances the rate of bromination and stabilizes the intermediate cyclopropyl bromonium cations against ring opening in the course of bromine addition. Calculations at the B3LYP/6-311G(d,p) level show that unsymmetrical bromonium ions are the intermediates, and that they are stabilized by the spiroannelation with cyclopropane rings. The bromonium ion derived from 1 is less stable by 6.3 kcal mol(-1) than that from isobutene. One or two spirocyclopropane rings as in 3 and 4 stabilize the corresponding bromonium. ion by 9.6 and 16.4 kcal mol(-1), respectively, while one or two alpha-cyclopropyl substituents as in ethenylcyclopropane (7) and 1,1-dicyclopropylethene (8) stabilize the corresponding bromonium ions by 13 and 29 kcal mol-1, respectively. The experimental bromination rates of all the studied alkenes correlate reasonably well (r(2) = 0.93) With calculated relative energies of the corresponding bromonium ions. The correlation is even better within the series of methylenecyclopropanes 1, 3, and 4 (r(2) = 0.974) and bicyclopropylidenes 2, 5, and 6 (r(2) = 0.999). The experimental bromination rates also correlate fairly well with the first ionization energies of the corresponding alkenes 1-12 (with r(2) = 0.963) and 13-19 (with r(2) = 0.991). The calculated preferred nucleophilic attack of a water molecule at both the C-1' and C-1 atoms of representative bromonium ions conforms well to the experimentally observed product distribution."],["dc.identifier.doi","10.1021/jo0162686"],["dc.identifier.isi","000176173700016"],["dc.identifier.pmid","12054944"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/42922"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Chemical Soc"],["dc.relation.issn","0022-3263"],["dc.title","Reactivities of methylenetriangulanes and spirocyclopropanated bicyclopropylidenes toward bromine. Relative stabilities of spirocyclopropanated versus methyl-substituted bromonium ions"],["dc.type","review"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]