Volume 2008, Issue 34 p. 5367-5372
Full Paper

Combination of 1,2-Hydroboration and 1,1-Organoboration: A Convenient Route to 5-Silaspiro[4,4]nona-1,6-diene Derivatives

Ezzat Khan

Ezzat Khan

Anorganische Chemie II, Universität Bayreuth, 95440 Bayreuth, Germany, Fax: +49-921-552157

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Bernd Wrackmeyer

Bernd Wrackmeyer

Anorganische Chemie II, Universität Bayreuth, 95440 Bayreuth, Germany, Fax: +49-921-552157

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Rhett Kempe

Rhett Kempe

Anorganische Chemie II, Universität Bayreuth, 95440 Bayreuth, Germany, Fax: +49-921-552157

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First published: 17 November 2008
Citations: 12

Graphical Abstract

Dialkyn-1-yl(divinyl)silanes react with 9-borabicyclo[3.3.1]nonane (9-BBN) by 1,2-hydroboration followed by intramolecular 1,1-organoboration to give 5-silaspiro[4.4]nona-1,6-diene derivatives. Protodeborylation with excess acetic acid affords the respective spirosilanes bearing substituents only in 1,6-positions. Multinuclear NMR spectroscopy (1H, 11B, 13C, 29Si NMR) and X-ray structural analysis served for the characterization of the new spirosilanes.

Abstract

Dialkyn-1-yl(divinyl)silanes were prepared and their reactions with 9-borabicyclo[3.3.1]nonane (9-BBN) were studied. 1,2-Hydroboration takes place selectively at the vinyl group, followed by intramolecular 1,1-organoboration to form a 1-silacyclopent-2-ene ring. Repetition of this sequence affords, in essentially quantitative yield, 5-silaspiro[4,4]nona-1,6-diene derivatives bearing substituents in the 1,6-positions and 9-borabicyclo[3.3.1]nonyl groups in the 2,7-positions. Protodeborylation with an excess amount of acetic acid gives the respective spirosilanes bearing substituents only in the 1,6-positions. All new compounds were characterized by NMR spectroscopy in solution (1H, 11B, 13C, 29Si NMR) and for two examples of the spirosilanes by X-ray structural analysis in the solid state. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)