Trimethylsilylacetic acid

Handling, Storage, and Precautions prone to isomerization and should not be stored for extensive periods. 

Anionic Reactions. In a manner similar to o -silyl esters, trimethylsilylacetic acid (1) can be used to prepare a,fi-unsaturated carboxylic acids from carbonyl compounds by a Peterson alkenation reaction (eq 1). However, the dianion of acid (1) is required. The yields are generally inferior to analogous reactions with a-silyl esters.  

A comprehensive review of all aspects of this reagent (770 references) up to 1995 has been published. See Rucker, C., Chem. Rev. 1995, 95, 1009. 

The dianion of acid (1) also reacts with alkyl halides to afford substituted a-trimethylsilylcarboxylic acids. With epoxides, the dianion provides )/-hydroxy acids that cyclize to a-silylbutyrolactones (eq 2) The resultant a-silyl lactones (2) are precursors to a wide variety of functionalized derivatives. The direct conversion of a butyrolactone to its a-sUyl analog is complicated by the competition of the 0-silylation pathway. 

Derivatives. TrimethylsUylacetyl thiolesters, which have been used as precursors to 8-lactams, are prepared by reaction of the appropriate thiol with the acid chloride derivative of (1). Acid (1) has also been used as a precursor to l-diazo-3-trimethylsilyl-acetone, which provides cyclopropyl trimethylsilylmethyl ketones upon reaction with alkenes, through reaction of the acid chloride or a mixed anhydride derivatives of the acid (1) with diazomethane.  

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Trimethylsilylacetic acid forms adducts with carbonyl compounds which undergo spontaneous elimination.55 The unsaturation produced appears solely in the a, P-positions, but E and Z isomers are formed in... 

TRIFLUOROMETHYL SULFIDES Trifluoromethylthiocopper. a-TRIMETHYLSILYL ACIDS TrimethyMylacetic acid. a-TRIMETHYLSILYL-7-BUTYROLACTONES Trimethylsilylacetic acid. TRIMETHYLSILYLENOL ETHERS Bis(trimethyl ilyl)formamide. Zinc. TRIMETHYLSILYLETHYNYL KETONES Cuprous trimethylsilylacetylide. TROPONES Diiron nonacarbonyL TROPONOIDS Diiron nonacarbonyL... 

Trimethylsiloxy-2-pentene, 227 Trimethylsilylacetic acid, 509 Trimethylsilylacetyl chloride, 509 Trimethylsilylarenes, 514 Trimethylsilyl carbamates, 263 Trimethylsilylcarbene, 307-308 Trimethylsilyl cyanide, 133... 

Trimethylsilylacetyl chloride, (CH3)3SiCH2COCl (1). Mol. wt. 148.67. This acid chloride is prepared by reaction of oxalyl chloride with trimethylsilylacetic acid (6, 631-632). 

Trimethylsilylacetic acid treated at 0° with 2.2 equivalents Li-diisopropylamide in tetrahydrofuran, then at -78 with cyclohexanone cyclohexylideneacetic acid. Y 83%. F. e. and reactions s. P. A. Grieco, C. J. Wang, and S.D. Burke, Chem. Commun. 1975, 537. 

Related Reagents. f-Butyl a-Lithiobis(trimethylsilyl)acetate f-Butyl Trimethylsilylacetate Ethyl Bromozincacetate Ethyl Lithioacetate Ethyl Trimethylsilylacetate Ketene Bis(trimethyl-silyl) Acetal Ketene f-Butyldimethylsilyl Methyl Acetal l-Methoxy-2-trimethylsilyl-l-(trimethylsilyloxy)ethylene Methyl (Methyldiphenylsilyl)acetate Methyl 2-Trimethylsilyl-acrylate Triethyl Phosphonoacetate Trimethylsilylacetic Acid. 

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

Preparative Methods most often prepared (eq 1) by pyrolysis of ethoxy(trimethylsilyl)acetylene at 120 °C (100 mmol scale, 65% yield). Recently, pyrolysis of t-butoxy(trimethylsilyl) acetylene has been shown to be a convenient alternative for the preparation of trimethylsilylketene (1). Thermal decomposition of t-butoxy(trimethylsilyl)acetylene causes elimination of 2-methylpropene slowly at temperatures as low as 50 °C and instantaneously at 100-110 °C (30 mmol scale, 63% yield). The main advantage of this method is that it is possible to generate trimethylsilylketene in the presence of nucleophiles, leading to in situ trimethylsilylacetylation (eq 2). Increased shielding of the triple bond prevents problems such as polymerization and nucleophilic attack that occur when the ketene is generated in situ from (trimethylsilyl)ethoxyacetylene. Trimethylsilylketene can also be prepared (eq 3) via the dehydration of commercially available trimethylsilylacetic acid with 1,3-dicyclohexylcarbodiimide (DCC) in the presence of a catalytic amount of triethylamine (100 mmol scale, 63%). Other typical methods used for ketene generation such as dehy-drohalogenation of the acyl chloride and pyrolysis of the... 

A -(Trimethylsilyl)acetamide, T-00338 yV-(Trimethylsilyl)acetanilide, see P-00210 Trimethylsilylacetic acid, T-00339 (Trimethylsilyl)acetyl chloride, in T-00339 Trimethylsilyl bromide, see B-00582... 

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