Ethyl trimethylsilylacetate

The Q -(methyldiphenylsilyl) ketones isomerize to the corresponding silyl enol ether regioselectively simply by mild thermolysis at about 150 °C (eq 6). This reaction can also be done in a stereoselective fashion to give the (Z)-enol silyl ether when the thermolysis is carried out in acetonitrile (eq 7).  

Related Reagents. f-Butyl Trimethylsilylacetate Dimethyl-2-(trimethylsilyl)acetamide Ethyl (Methyldiphenyl-silyl)acetate Ethyl Trimethylsilylacetate Trimethylsilylacetic Acid Trimethylsilylacetone. 

Solubility sol ethereal and chlorinated solvents reacts with protic solvents. 

Preparative Methods available by a Reformatsky reaction from ethyl bromoacetate, and by reaction of trimethylsilylmethyl-magnesium chloride with ethyl chloroformate. An alternative approach requires the treatment of ethyl acetate with triph-enylmethylsodium 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 0-silylation to 90%. Similar methods can be used to prepare analogs. 

Handling, Storage, and Precautions reacts with protic solvents to give the desilylated product. 

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Use of ethyl trimethylsilylacetate (detailed preparation given) and TBAF (drying details Fluka trihydrate dried over P2Os/48 h/0.1 mmHg, and then powdered in a dry atmosphere) for the preparation of (Z)-3-trimethylsilyl-ioxypent-2-ene from pentan-3-one. 

Trimethylsilylation of enolizable carbonyl compounds and alcohols has also been accomplished by the fluoride ion promoted reaction with hexamethyldisilane and ethyl trimethylsilylacetate [48, 49], with high stereospecificity giving Z-enol ethers from ketones [50]. l-Trimethylsilyl-(l-trimethylsilyloxy)alkanes, produced from the reaction of aldehydes with hexamethyldisilane, undergo acid-catalysed hydrolysis during work up to yield the trimethylsilylcarbinols [51]. In the case of aryl aldehydes, the initially formed trimethylsiloxy carbanion produces the pinacol (Scheme 3.1). 

Trimethylsilylation of enolizable ketones using ethyl trimethylsilylacetate ... 

The Peterson reaction of the chlorovinyl-complex with ethyl trimethylsilylacetate provided the 11Z isomer preferentially (77%), and the 1 IE isomer as a secondary product (15%). The ester was transformed into the C 8 ketone (PhsSnCfy, BuLi, Et20, 79%). Reaction with (/Pr0)2P(0)CH2CN afforded the 1 lZ-retinonitrile in 73% yield. The complex was removed by CuC (72%) and DIBAL-H reduction led quantitatively to 1 lZ-retinal, Fig. (24). 

Silylation of acidic compounds.2 The combination of ethyl trimethylsilylacetate and 2-5 mole % of tetra-n-butylammonium fluoride (TBAF) is a markedly efficient reagent for transfer of trimethylsilyl groups to relatively acidic substrates such as ketones, alcohols, thiols, phenols, and carboxylic acids, and even 1-alkynes. KOCH3/ (18-crown-6) and Triton B are also effective catalysts. 

Distil the remaining liquid through a 15 cm Vigreux column at reduced pressure. This affords ethyl trimethylsilylacetate 12 as a colourless liquid which exhibits a pleasant and characteristic odour, 58.5-65 g, 61-68%, b.p. = 82-84°C (47 mm), 93-94°C (105 mm). The product is stable to standard manipulations and can be stored for extended periods of time. 

SILYLATION OF KETONES WITH ETHYL TRIMETHYLSILYLACETATE (Z)-3-TRIMETH YLSILOX Y-2-PENTENE... 

Ethyl trimethylsilylacetate has also been used for the synthesis of a, (3-unsaturated esters.16 The chemistry of tetrabutylammonium fluoride as a base with mild reactivity has been reviewed.17... 

Ethyl trimethylsilylacetate Acetic acid, (trimethylsily 1)-, ethyl ester (8, 9) (4071-88-9)... 

The aldol reaction can also be effected by reaction of the ketone and the aldehyde m the presence of excess ethyl trimethylsilylacetate (7, 150-151) and TBAF in THF (equation II). 

PETERSON REACTION Alkyidimesitylboranes. Chloromethyldiphdnylsilane. Ethyl trimethylsilylacetate. Lithium l-(dimethyl-amino)naphthalenide. Methyldiphenylchlo-rosilane. Phenylsulfonyl(trimethylsilyl)-methane. Titanium(IV) isopropoxide, Tri-methylsilylmethylmagnesium chloride. 

Ethyl trimethylsilylacetate is stable to the usual manipulations, and can be stored in glass containers for years without change of physical and spectral properties IR (liquid film) cm 1720, characteristic of a-silyl esters The reported physical constants are bp 16-lTC (40 mm),... 

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