Show simple item record Tomazela, Daniela Maria Moraes, Luiz Alberto Beraldo Pilli, Ronaldo Aloise Eberlin, Marcos Nogueira 2016-10-10T20:51:12Z 2016-10-10T20:51:12Z 2002
dc.identifier.citation Tomazela, Daniela Maria et al. Mannich-Type reactions in the Gas-Phase: the addition of Enol Silanes to cyclic N-Acyliminium Ions. The Journal Organic Chemistry, v. 67, n. 14, p. 4652-4658, 2002. Disponível em: <>. Acesso em: 10 Out. 2016. pt_BR
dc.identifier.issn 0022-3263
dc.description.abstract The intrinsic gas-phase reactivity of cyclic N-acyliminium ions in Mannich-type reactions with the parent enol silane, vinyloxytrimethylsilane, has been investigated by double- and triple-stage pentaquadrupole mass spectrometric experiments. Remarkably distinct reactivities are observed for cyclic N-acyliminium ions bearing either endocyclic or exocyclic carbonyl groups. NH-Acyliminium ions with endocyclic carbonyl groups locked in s-trans forms participate in a novel tandem N-acyliminium ion reaction:  the nascent adduct formed by simple addition is unstable and rearranges by intramolecular trimethylsilyl cation shift to the ring nitrogen, and an acetaldehyde enol molecule is eliminated. An NSi(CH3)3-acyliminium ion is formed, and this intermediate ion reacts with a second molecule of vinyloxytrimethylsilane by simple addition to form a stable acyclic adduct. N-Acyl and N,N-diacyliminium ions with endocyclic carbonyl groups, for which the s-cis conformation is favored, react distinctively by mono polar [4+ + 2] cycloaddition yielding stable, ressonance-stabilized cycloadducts. Product ions were isolated via mass-selection and structurally characterized by triple-stage mass spectrometric experiments. B3LYP/6-311G(d,p) calculations corroborate the proposed reaction mechanisms. pt_BR
dc.language.iso eng pt_BR
dc.rights restrict access pt_BR
dc.title Mannich-Type reactions in the Gas-Phase: the addition of Enol Silanes to cyclic N-Acyliminium Ions pt_BR
dc.type article pt_BR
dc.identifier.doi 10.1021/jo016382o pt_BR

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