Synlett 2015; 26(07): 995-996
DOI: 10.1055/s-0034-1380459
© Georg Thieme Verlag Stuttgart · New York


Szymon Jarzyński
Department of Organic and Applied Chemistry, Faculty of Chemistry, University of Łódź, Tamka 12, 91-403 Łódź, Poland   Email:
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Publication History

Publication Date:
12 March 2015 (online)


Triethoxysilane (TES) is an important chemical reagent in the synthesis of various organosilicon compounds. It is a colourless transparent liquid (bp 134–135 °C) with a characteristic ether odour. Triethoxysilane is an organosilane and has been widely used in organic synthesis as a mild reducing agent. It has been used for asymmetric hydrosilylation of ketones in order to obtain the corresponding alcohols.[1] Additionally, (EtO)3SiH is applied as silylation reagent in regio- and stereoselective hydrosilylations.[2] It is able to cleave a C–C bond of the four-membered ring of biphenylene forming the corresponding 2-silylbiphenyls.[3] TES is also used in reductive etherification of aldehydes in the presence of the catalyst system InCl3/TMSCl.[4]

Triethoxysilane is commercially available but it can also easily be synthesized in the reaction of trichlorosilane with anhydrous ethyl alcohol (Scheme [1]).[5]

Zoom Image
Scheme 1

Table 1 Use of Triethoxysilane

(A) Beller and co-workers described a procedure for efficient reduction of tertiary amides. The reaction was carried out in the presence of inexpensive zinc catalyst with (EtO)3SiH under mild conditions.[6] Diverse functional groups present in the molecule (ester, ether, nitro, cyano, azo) are tolerated. The desired products were isolated in good to high yields.

(B) An efficient rhodium(I)-catalyzed reaction between arenediazonium tosylate salts and triethoxysilane led to aryltriethoxysilanes in good to high yields.[7] The synthesis was carried out in the presence of Bu4NI and Et3N.

(C) The preparation of various nitriles from primary carboxylic amides can be realized by iron-catalyzed [Et3NH, HFe3(CO)11] dehydration with triethoxysilane as dehydrating agents. The experiment was carried out using toluene as a solvent in 100 °C.[8]

(D) Ritter and co-workers reported a selective 1,2-hydrosilylation of conjugated dienes using triethoxysilane in the presence of catalytic amounts of platinum precatalyst. The catalyst was activated with methylmagnesium chloride (MeMgCl) at –45 °C, then (EtO)3SiH and diene were added. The mixture was heated to 50 °C. The product was formed with high selectivity.[9]

(E) Organosilanes are convenient reagents in the selective reduction of nitroarenes. The corresponding aniline was formed with (EtO)3SiH in the presence of a catalyst consisting of FeBr2 and Ph3P. The desired product was isolated in good yield (66%).[10]

(F) Riand and co-workers described the stereodivergent synthesis of polysubstituted enynes, which are useful building blocks. Vinylsiloxanes (Z)-2 and (E)-2 were obtained in high yields with an α/β selectivity of 80:20. These products were then converted into trisubstituted enynes, which were isolated with full retention of the stereochemistry.[11]

(G) The asymmetric silylcyclization of 1,6-enynes with (EtO)3SiH was carried out in the presence of a rhodium catalyst generated in situ.[12] It was observed that these reactions provide optically active silylalkylidene cyclopentane and pyrrolidine derivatives. These products were formed in good yields and with high enantioselectivities.

(H) (EtO)3SiH can be applied as a mild reducing agent for catalytic reductive dehydration of tertiary amide to the corresponding enamine catalyzed by potassium tert-butoxide (t-BuOK).[13] The reaction leading to the enamine proceeded with high conversion ratio.

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