| | 1 | Author
| Z. Naturforsch | Requires cookie* | | | Title
| ,1-Organoboration of Sterically Hindered Tetra-l-alkynylsilanes and the Crystal Structure of Tetrakis[l-(3,3-dimethyl)butynyl]silane  | | | | Abstract
| Tetra-l-alkynylsilanes, Si(C sC R *)4 with R 1 = 'Bu (1) and SiMe3 (2) react with triethyl-borane, E t3B. by intermolecular 1,1-ethyloboration followed by intramolecular 1.1-vinylo-boration. to give the substituted siloles 3 and 5 with two R 'C = C groups linked to silicon. The formation of 5 (R 1 = SiMe3) requires exactly one equivalent of E t3B, whereas 3 (R 1 = 'Bu) is formed after = 2 0 d in boiling toluene in the presence of a large excess of E t3B, and the remaining 'B u -C = C groups in 3 do not react with E t3B. The 1,1-organoboration of 2 using one equivalent of 9-ethyl-9-borabicyclo[3.3.1]nonane, Et-9-BBN, proceeds similar to the E t3B-reaction, to give mainly the silole derivative 6, in which the bicyclic ring system is enlarged by two carbon atoms. This product is the result of a kinetically controlled reaction. The single crystal X-ray analysis of 1 has been carried out (space group Pnm a; a = 990.0(2), b = 1668.0(3), c = 1479.0(3) pm), and its crystal structure is com pared with that of the corre sponding tin compound 1 (Sn). | | | |
Reference
| Z. Naturforsch. 51b, 1320—1324 (1996); received March 14 1996 | | | |
Published
| 1996 | | | |
Keywords
| Tetra-l-alkynylsilanes, 1, 1-Organoboration, Siloles, X-Ray | | | |
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| default:Reihe_B/51/ZNB-1996-51b-1320.pdf | | | | Identifier
| ZNB-1996-51b-1320 | | | | Volume
| 51 | |
| 2 | Author
| B. Ernd, W. Rackm Eyer, D. Örfler, W. Olfgang Milius, M. Ax, H. Erberhold | Requires cookie* | | | Title
| ,1-Organoboration of Trimethyl-l-propynyltin Using Diorganoboryl-Substituted Ferrocenes | | | | Abstract
| The reactions of various diorganoborylferrocenes, F c -B R 2 [1, R = Me (a), Et (b), 'Pr (c), 'Bu (d), Ph (f), R2B = 9-borabicyclo[3.3.1]nonyl (e)] and 1,1 '-bis(9-borabicyclo[3.3.1]nonyl)-ferrocene (2) with trimethyl-l-propynyltin (3) were studied, and the products of the 1,1-organoboration were characterized as the alkenyltin compounds 4 -6 by 'H, UB, 13C and 119Sn NMR. In the cases of l a -I d and If, there is competition between the transfer of a ferrocenyl group and the other organyl groups R from boron to carbon, whereas in the case of the 9-borabicyclo[3.3.1]nonane derivatives le and 2, the enlargement of the bicyclic system takes place selectively (compounds 4e and 6). The molecular structure of the product 6, obtained from the reaction between the l,l'-diborylated ferrocene 2 and two equivalents of 3, was determined by single crystal X-ray analysis (space group P2x!c\ monoclinic; Z = 4, a = 958.3(2), b = 1610.4(3), c = 2405.3(5) pm and ß = 90.33(3)°). | | | |
Reference
| Z. Naturforsch. 51b, 851 (1996); received October 26. 1995 | | | |
Published
| 1996 | | | |
Keywords
| Ferrocenes, Trimethyl-l-propynyltin, 1, 1-Organoboration, Alkenyltin Compounds, X-Ray | | | |
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| default:Reihe_B/51/ZNB-1996-51b-0851.pdf | | | | Identifier
| ZNB-1996-51b-0851 | | | | Volume
| 51 | |
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