The simplest azabutadienes in their N-protonated forms. Generation, stability, and cycloaddition-reactivity in the gas phase

dc.creatorAugusti, R
dc.creatorGozzo, FC
dc.creatorMoraes, LAB
dc.creatorSparrapan, R
dc.creatorEberlin, MN
dc.date1998
dc.date45474
dc.date2014-12-02T16:26:01Z
dc.date2015-11-26T16:52:39Z
dc.date2014-12-02T16:26:01Z
dc.date2015-11-26T16:52:39Z
dc.date.accessioned2018-03-28T23:39:37Z
dc.date.available2018-03-28T23:39:37Z
dc.identifierJournal Of Organic Chemistry. Amer Chemical Soc, v. 63, n. 15, n. 4889, n. 4897, 1998.
dc.identifier0022-3263
dc.identifierWOS:000075263100008
dc.identifier10.1021/jo9715433
dc.identifierhttp://www.repositorio.unicamp.br/jspui/handle/REPOSIP/72458
dc.identifierhttp://www.repositorio.unicamp.br/handle/REPOSIP/72458
dc.identifierhttp://repositorio.unicamp.br/jspui/handle/REPOSIP/72458
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/1276343
dc.descriptionThe simplest azabutadienes, i.e. 1-aza-1,3-butadiene and 2-aza-1,3-butadiene, are generated in their N-protonated forms 1 and 2 via gas-phase dissociative electron ionization of allylamine and piperidine; respectively. Formation of 1 and 2 is suggested by simple dissociation mechanisms, and supported by high-accuracy G2 ab initio calculations, which show the ions to be stable, non-interconverting species. Whereas 1 and 2 are unreactive toward ethylene and cyclohexene, 2 reacts with alkenes activated by electron-donating (OC2H5), electron-withdrawing (CN; COCH3), and vinyl and phenyl substituents most likely by polar [4(+) + 2] cycloaddition, as suggested by MS3 experiments and ab initio calculations. The cycloadduct of 2 with ethyl vinyl ether is unstable and dissociates promptly by ethanol loss; hence, net C2H2 addition occurs. This novel vinylation reaction is proposed as a potential structurally diagnostic test for both 2-azabutadienes and vinyl ethers. Isomer 1 is in general much less reactive, and abundant adducts are only formed in reactions with alkenes activated by electron-withdrawing substituents. In reactions of 1 and 2 with esters (methyl acetate and dimethyl carbonate), hydrogen-bridged ion-neutral complexes are formed as the most abundant and stable products, as suggested by the ab initio calculations. Acetone, fluoroacetone and acetonitrile form abundant adducts with-bath 1 and 2; However, the experimental and theoretical results on these adducts provide nb clear structural information. Reactions of 1 with DMSO occur almost exclusively by proton transfer, whereas 2 forms an abundant complex with DMSO. Limited reactivity is observed for I and 2 with acetyl chloride and thionyl chloride; the minor products observed were those of either dissociative proton transfer or charge exchange.;The distinctive reactivities of 1 and 2 with styrene, ethyl vinyl ether, and dimethyl sulfoxide contrast to their identical low energy CID behavior, and allow their straightforward differentiation in the gas phase.
dc.description63
dc.description15
dc.description4889
dc.description4897
dc.languageen
dc.publisherAmer Chemical Soc
dc.publisherWashington
dc.publisherEUA
dc.relationJournal Of Organic Chemistry
dc.relationJ. Org. Chem.
dc.rightsfechado
dc.sourceWeb of Science
dc.subjectDiels-alder Reaction
dc.subjectPentaquadrupole Mass-spectrometer
dc.subjectMolecular-orbital Methods
dc.subjectRadical-cation
dc.subjectCarbonyl-compounds
dc.subjectAcylium Ions
dc.subjectBasis Sets
dc.subjectIsomers
dc.subjectTandem
dc.subjectDissociation
dc.titleThe simplest azabutadienes in their N-protonated forms. Generation, stability, and cycloaddition-reactivity in the gas phase
dc.typeArtículos de revistas


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