Pyrrolizidine alkaloids necine bases: II. Conformational analysis of free bases

dc.creatorGiordan, M
dc.date1998
dc.dateDEC
dc.date2014-12-02T16:26:44Z
dc.date2015-11-26T16:32:27Z
dc.date2014-12-02T16:26:44Z
dc.date2015-11-26T16:32:27Z
dc.date.accessioned2018-03-28T23:13:52Z
dc.date.available2018-03-28T23:13:52Z
dc.identifierJournal Of Computational Chemistry. John Wiley & Sons Inc, v. 19, n. 16, n. 1853, n. 1861, 1998.
dc.identifier0192-8651
dc.identifierWOS:000077130900006
dc.identifierhttp://www.repositorio.unicamp.br/jspui/handle/REPOSIP/58505
dc.identifierhttp://www.repositorio.unicamp.br/handle/REPOSIP/58505
dc.identifierhttp://repositorio.unicamp.br/jspui/handle/REPOSIP/58505
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/1270521
dc.descriptionMolecular mechanics calculations were applied to the conformational analysis of two diasteroisomers, the pyrrolizidine alkaloids (PAs) retronecine and heliotridine. The application of reoptimized parameters for H bonding corrected the tendency of MM3(92) calculations to give unrealistic H ... O distances for intramolecular OH interactions occurring in both diasterisomers. Inversions in the H-bond direction of exo-retronecine and in the relative stability of heliotridine endo-exo conformers were also observed with the application of the new parameters. A set of probable conformers was obtained for each diasterisomer, based on conformational and Boltzmann population analysis. Only exo-puckered conformers were found in the retronecine set, whereas both exo- and endo-puckered conformers were obtained for heliotridine. Transition state conformations supplied arguments supporting the design of models for H-bond interconversion in the case of exo-retronecine and for the exo-endo interconversion of heliotridine. Reactivity behaviors and H-1-NMR data of both diasterisomers were elucidated in light of the theoretical results. (C) 1998 John Wiley & Sons, Inc.
dc.description19
dc.description16
dc.description1853
dc.description1861
dc.languageen
dc.publisherJohn Wiley & Sons Inc
dc.publisherNew York
dc.publisherEUA
dc.relationJournal Of Computational Chemistry
dc.relationJ. Comput. Chem.
dc.rightsfechado
dc.rightshttp://olabout.wiley.com/WileyCDA/Section/id-406071.html
dc.sourceWeb of Science
dc.subjectpyrrolizidine alkaloids
dc.subjectnecine bases
dc.subjectretronecine
dc.subjectheliotridine
dc.subjectconformational analysis
dc.subjectmolecular structure
dc.subjecthydrogen bond
dc.subjectmolecular mechanics
dc.subjectBiosynthesis
dc.titlePyrrolizidine alkaloids necine bases: II. Conformational analysis of free bases
dc.typeArtículos de revistas


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