Ethyl (trimethylsilyl)acetate

Preparation

ethyl trimethylsilylacetate synthesis: Available by a Reformatsky reaction from ethyl bromoacetate, and by reaction of trimethylsilylmethylmagnesium chloride with ethyl chloroformate. An alternative approach requires the treatment of ethyl acetate with triphenylmethylsodium followed by chlorotrimethylsilane The use of a nitrogen base with ethyl acetate in THF followed by reaction with chlorotrimethylsilane results in a mixture of C- and O-silylation. The use of HMPA as additive in the reaction medium increases the amount of O-silylation to 90%. Similar methods can be used to prepare analogs.

Purification Methods

Purify it by distilling ca 10g of reagent through a 15cm, Vigreux column (p 11) and then redistilling it through a 21cm glass helices-packed column [Hauze & Hauser J Am Chem Soc 75 994 1953]. Alternatively, dissolve it in Et2O, wash with H2O, dilute Na2CO3, dry over Na2CO3, evaporate Et2O, and distil it through a column of 15 theoretical plates. [Gold et al. J Am Chem Soc 70 2874 1948, Beilstein 4 IV 3974.]

General Description

Reaction of ethyl trimethylsilylacetate (ETSA) with dilute hydrochloric acid, dilute alkali, anhydrous HCl, anhydrous bromine and absolute ethanol has been reported. ETSA undergoes condensation with aromatic aldehydes in the presence of base catalyst to yield β-trimethylsiloxycarboxylates. Lithium ETSA reacts with ketones to yield α,β-unsaturated esters.