B(C6F5)3-guided cyclotrimerization-rearrangement of phenylacetylene. Evidence of the (C6F5)3B-–C(H)=C$\mathplus$Ph intermediate in a 1,1-carboboration reaction

Авторы: Nie Wanli, Sun Guofeng, Tian Chong, Borzov Maxim V.
Журнал: Zeitschrift für Naturforschung B
Том: 71
Номер: 10
Год издания: 2016
Первая страница: 1029
Последняя страница: 1041
DOI: 10.1515/znb-2016-0110
Аннотация: In presence of 2,2,6,6-tetramethylpiperidinium ([TMPH]+) chlorotris(pentafluorophenyl)borate ([TMPH]+[ClB(C6F5)3]−, 3), phenylacetylene undergoes an unusual cyclotrimerization-rearrangement leading to tris(pentafluorophenyl)(3,4,5-triphenylphenyl)borate anion (1) as a minor product which can be isolated and purified in a form of salts [1·(TMPH)n·Cl(n–1)] (n = 3 or 5). A variable temperature and concentration NMR spectroscopy study of 3 in CDCl3 unambiguously demonstrated its ability to liberate free B(C6F5)3, which initiates cyclotrimerization and guides rearrangements towards formation of the tetraarylborate anion 1. For the previously studied “spectator” reaction between phenylacetylene and B(C6F5)3 in CDCl3, 1H, 19F, and 11B NMR-spectral evidence of the (C6F5)3B−–C(H)=C+Ph zwitterionic intermediate of the 1,1-carboboration reaction has been demonstrated. The crystal structures of [1·(TMPH)3·Cl2], the salt 3, and a 1:1 adduct of 1,3,5-tris(4-fluorophenyl)benzene and 2,4,6-tris(pentafluorophenyl)-1,3,5,2,4,6-trioxatriborinane (2) have been established by X-ray diffraction analysis.
Добавил в систему: Борзов Максим Владимирович

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