Synthesis of silyl ethers

Name Reactions

Protecting Groups

Recent Literature

A commercially available proazaphosphatrane is an efficient and mild catalyst for the silylation of a wide variety of alcohols and phenols, including acid-sensitive, base-sensitive, and hindered substrates, using tert-butyldimethylsilyl chloride (TBDMSCl). The reactions are carried out in acetonitrile from 24 to 40°C and on rare occasions in DMF from 24 to 80°C. Although representative primary alcohols, secondary alcohols, and phenols were silylated using the more sterically hindered reagent tert-butyldiphenylsilyl chloride (TBDPSCl), tertiary alcohols were recovered unchanged.
B. A. D'Sa, J. G. Verkade, J. Am. Chem. Soc., 1996, 118, 12832-12833.

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

Two methods are described for the regioselective displacement of the primary hydroxy group in methyl glycosides with iodide. Products of the first method employing triphenylphosphine and iodine need purification on a reverse phase column. A one-pot procedure via sulfonates and subsequent substitution with iodide and methods for the protection of the iodoglycosides are also described.
P. R. Skaanderup, C. S. Poulsen, L. Hyldtoft, M. R. Jørgensen, R. Madsen, Synthesis, 2002, 1721-1727.

A one-pot alkylation-silylation reaction of various epoxides with R₃Al-R'₃SiOTf occurs stereospecifically to give the corresponding alkylation-silylation products in excellent yields.
P. Shanmugam, M. Miyashita, Org. Lett., 2003, 3265-3268.

A new procedure for catalytic reductive coupling of aldehydes and alkynes uses Ni(COD)₂ with an imidazolium carbene ligand as the catalyst and triethylsilane as the reducing agent.
G. M. Mahandru, G. Liu, J. Montgomery, J. Am. Chem. Soc., 2004, 126, 3698-3699.

The rhenium-catalyzed hydrosilation of aldehydes and ketones under ambient temperature and atmosphere gave protected alcohol as silyl ether in good yields. The mechanism is discussed.
E. A. Ison, E. R. Trivedi, R. A. Corbin, M. M. Abu-Omar, J. Am. Chem. Soc., 2005, 127, 15374-15375.

Optimizations to generate CuH in situ have led to an efficient and inexpensive hydrosilylation method for dialkyl ketones.
B. H. Lipshutz, C. C. Caires, P. Kuipers, W. Chrisman, Org. Lett., 2003, 5, 3085-3088.

Aliphatic carboxyl derivatives (acids, acyl chlorides, esters) and aldehydes were efficiently reduced to the methyl group by HSiEt₃ in the presence of catalytic amounts of B(C₆F₅)₃. Aromatic carboxylic acids, as well as other carbonyl functional equivalents, underwent smooth partial reduction to the corresponding TES-protected benzylic alcohols in competition with a Friedel-Crafts-like alkylation decreasing the overall selectivity of the reduction process.
V. Gevorgyan, M. Rubin, J.-X. Liu, Y. Yamamoto, J. Org. Chem, 2000, 66, 1672-1675.

A β-amino alcohol-Ti(Oi-Pr)₄ complex has been shown to catalyze the enantioselective cyanosilylation of aldehydes efficiently. Aromatic, conjugated, heteroaromatic, and aliphatic aldehydes were converted to their corresponding cyanohydrin trimethylsilyl ethers in 90-99% yields with up to 94% ee under mild conditions in the presence of 5 mol-% of the complex catalyst.
Y. Li, B. He, B. Qin, X. Feng, G. Zhang, J. Org. Chem., 2004, 69, 7910-7913.

Combinations of N-oxides and Ti(OiPr)₄ act as bifunctional catalysts in the cyanosilylation of ketones. The reaction is promoted by the dual action of these new titanium complexes via activation of the ketone by the titanium and of TMSCN by the N-oxide.
Y. Shen, X. Feng, Y. Li, G. Zhang, Y. Jiang, Tetrahedron, 2003, 59, 5667-6675.