Improved Synthesis of Aryltrialkoxysilanes via Treatment of Aryl Grignard or Lithium Reagents with Tetraalkyl Orthosilicates
Amy S. Manoso, Chuljin Ahn, Arash Soheili, Christopher J. Handy, Reuben Correia, W. Michael Seganish and Philip DeShong*
*Department of Chemistry and Biochemistry, University of Maryland, College
Park, Maryland 20742, Email: deshong
umd.edu
A. S. Manoso, C. Ahn, A. Soheili, C. J. Handy, R. Correia, W. Seganish, P. DeShong, J. Org. Chem., 2004, 69, 8305-8314.
DOI: 10.1021/jo048667h
Abstract
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.
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Details
The document details an improved method for synthesizing aryl(trialkoxy)silanes using aryl Grignard or lithium reagents with tetraalkyl orthosilicates. The study, conducted by researchers at the University of Maryland, demonstrates that ortho-, meta-, and para-substituted bromoarenes can be efficiently metalated and silylated at low temperatures to produce aryl siloxanes. The optimal conditions for Grignard reagents involve adding arylmagnesium reagents to 3 equivalents of tetraethyl or tetramethyl orthosilicate at -30°C in THF, while aryllithium species are silylated using 1.5 equivalents of the orthosilicate at -78°C in ether. The method avoids the formation of di- and triarylated byproducts, yielding predominantly monoaryl siloxanes. The study also explores the silylation of heteroaromatic substrates, with mixed results. The use of tetraalkyl orthosilicates is highlighted for its commercial availability, low cost, and ease of handling. This methodology provides a practical approach for synthesizing highly functionalized aryl siloxane derivatives, which are valuable in siloxane coupling technologies and the synthesis of complex molecules like antitumor antibiotics. The research was supported by the National Cancer Institute and the University of Maryland.
R. Correia, P. DeShong, J. Org. Chem., 2001, 66, 7449-7455.
Palladium-Catalyzed Arylation of Allylic Benzoates Using Hypervalent Siloxane Derivatives
R. Correia, P. DeShong, J. Org. Chem., 2001, 66, 7159-7165.
Key Words
ID: J42-Y2004-2470
