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1996 (2)
1Author    Z. NaturforschRequires 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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 TEI-XML for    default:Reihe_B/51/ZNB-1996-51b-1320.pdf 
 Identifier    ZNB-1996-51b-1320 
 Volume    51 
2Author    B. Ernd, W. Rackm Eyer, D. Örfler, W. Olfgang Milius, M. Ax, H. ErberholdRequires 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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 TEI-XML for    default:Reihe_B/51/ZNB-1996-51b-0851.pdf 
 Identifier    ZNB-1996-51b-0851 
 Volume    51