B(C6F5)3-Catalyzed Silation of Alcohols: A Mild, General Method for Synthesis of Silyl Ethers

James M. Blackwell, Katherine L. Foster, Victoria H. Beck and Warren E. Piers*

*Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada, Email: wpiersucalgary.ca

J. M. Blackwell, K. L. Foster, V. H. Beck, W. E. Piers, J. Org. Chem., 1999, 64, 4887-4892.

DOI: 10.1021/jo9903003 (free Supporting Information)

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Abstract

Tris(pentafluorophenyl)borane, B(C₆F₅)₃, is an effective catalyst for a mild and efficient dehydrogenative silation of alcohols using a variety of silanes. Only the most bulky silanes (Bn₃SiH and iPr₃SiH) were not reactive under these conditions. Generally, the reactions are clean and high yielding, with dihydrogen as the only byproduct. Primary aliphatic alcohols are silated cleanly but slowly, whereas secondary and tertiary alcohols react more rapidly. The reaction tolerates many functional groups inlcuding alkenes, alkynes, aliphatic ketones, esters, furans, and nitro. The selectivity of the silation reactions are roughly governed by the relative basicity of the present functional groups with more basic groups being selectively silated. The mechanism is discussed.

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Key Words

Silylation, TBDMS Ethers, TBDPS Ethers

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ID: J54-Y1999-380