Applications of Triethylsilane

Triethylsilane serves as an exemplar for organosilicon hydride behavior as a mild reducing agent. It is frequently chosen as a synthetic reagent because of its availability, convenient physical properties, and economy relative to other organosilicon hydrides which might otherwise be suitable for effecting specific chemical transformations.

Applications

A number of metal complexes catalyze the hydrosilylation of various carbonyl compounds by triethylsilane. Stereoselectivity is observed in the hydrosilylation of ketones as in the reactions of 4-t-butylcyclohexanone and triethylsilane catalyzed by ruthenium, chromium, and rhodium metal complexes (eq 4). Triethylsilane and Chlorotris(triphenylphosphine)rhodium(I) catalyst effect the regioselective 1,4-hydrosilylation of α,β-unsaturated ketones and aldehydes.Reduction of mesityl oxide in this manner results in a 95% yield of product that consists of 1,4- and 1,2-hydrosilylation isomers in a 99:1 ratio (eq 5). This is an exact complement to the use of phenylsilane, where the ratio of respective isomers is reversed to 1:99.

Generation of Other Triethylsilyl Reagents, etc. Triethylsilane is also used in the synthesis of various other reagents for organic synthesis. Triethylsilyl cyanide, which is used for the silylcyanation of aldehydes and ketones, can be prepared from Et₃SiH and acetonitrile in the presence of catalytic amounts of Cp(CO)₂FeMe.Bromotriethylsilane is prepared when Et₃SiH reacts with copper bromide and catalytic amounts of copper iodide or with PdCl₂ and allyl bromide.

Et₃SiH can also reduce Bu₃SnCl to Bu₃SnH, which when carried out in the presence of alkynes, allenes, or alkenes can undergo Lewis acid promoted hydrostannation reactions.This represents the first example of Lewis acid catalyzed hydrostannations with in situ generated tributyltin hydride. Significantly, Et₃SiH succeeded in this reaction where hydrosiloxanes failed. Lastly, Et₃SiH reacts with indium(III) chloride to generate dichloroindium hydride.

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