Synthesis of arylsiloxanes
General reaction conditions for the synthesis of aryl(trialkoxy)silanes from aryl Grignard and lithium reagents and tetraalkyl orthosilicates (Si(OR)4) have been developed. Ortho-, meta-, and para-substituted bromoarenes underwent efficient metalation and silylation at low temperature to provide aryl siloxanes.
A. S. Manoso, C. Ahn, A. Soheili, C. J. Handy, R. Correia, W. Seganish, P. DeShong, J. Org. Chem., 2004, 69, 8305-8314.
High yields were achieved by using [Rh(cod)(MeCN)2]BF4 as catalyst in a specific silylation of aryl iodides and bromides with triethoxysilane in the presence of NEt3. This new reaction tolerates different functional groups and therefore often eliminates the need to use protective groups (compared to previous methods via Grignard reagents).
M. Murata, M. Ishikura, M. Nagata, S. Watanabe, Y. Masuda, Org. Lett., 2002, 4, 1843-1845.
The silylation of various aryl iodides with 1,1,1,3,5,5,5-heptamethyltrisiloxane was achieved using transition-metal catalysts, such as Pd(0), Pt(0), and Rh(I), which offer a dramatically different substrate scope.
M. Murata, K. Ota, H. Yamasaki, S. Watanabe, Y. Masuda, Synlett, 2007, 1387-1390.
An efficient rhodium-catalyzed method allows the preparation of aryltriethoxysilanes from arenediazonium tosylate salts. A new method for hydrodediazoniation has also been explored.
Z. Y. Tang, Y. Zhang, T. Wang, W. Wang, Synlett, 2010, 804-808.
Treatment of substituted arylbromides with tert-butyllithium in diethyl ether at -78˚C, followed by the addition to dichlorodiethoxysilane, leads to the quantitative formation of diaryldiethoxysilanes. Diaryldiethoxysilanes can be reduced to the corresponding diarylsilanes by stirring with lithium aluminum hydride in diethyl ether. This method avoids the handling of gaseous and explosive dichlorosilane.
P. Gigier, W. A. Herrmann, F. E. Kühn, Synthesis, 2010, 1431-1432.