Trimethylsilylacetic Acid1

[2345-38-2]  · C5H12O2Si  · Trimethylsilylacetic Acid  · (MW 132.26)

(preparation of a,b-unsaturated carboxylic acids and a-trimethylsilylbutyrolactones2)

Physical Data: mp 40 °C.

Solubility: sol ethereal solvents.

Preparative Methods: obtained from the reaction of Trimethylsilylmethylmagnesium Chloride with Carbon Dioxide;3 can also be prepared by reaction of Acetic Acid with 2 equiv of Lithium Diisopropylamide, followed by Chlorotrimethylsilane and hydrolysis.4

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

Anionic Reactions.

In a manner similar to a-silyl esters, trimethylsilylacetic acid (1) can be used to prepare a,b-unsaturated carboxylic acids from carbonyl compounds by a Peterson alkenation reaction (eq 1).1 However, the dianion of acid (1) is required.2 The yields are generally inferior to analogous reactions with a-silyl esters.5

The dianion of acid (1) also reacts with alkyl halides to afford substituted a-trimethylsilylcarboxylic acids.2 With epoxides, the dianion provides g-hydroxy acids that cyclize to a-silylbutyrolactones (eq 2).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-silyl analog is complicated by the competition of the O-silylation pathway.

Derivatives.

Trimethylsilylacetyl thiolesters, which have been used as precursors to b-lactams, are prepared by reaction of the appropriate thiol with the acid chloride derivative of (1).6 Acid (1) has also been used as a precursor to 1-diazo-3-trimethylsilylacetone, 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.4

Silylacetic acids undergo a thermal rearrangement to afford the silyl ester (eq 3). The same migration of the silyl group is observed at lower temperatures when base catalysis is employed.7

Related Reagents.

t-Butyl a-Lithiobis(trimethylsilyl)acetate; t-Butyl Trimethylsilylacetate; Dilithioacetate; Ethyl Lithio(trimethylsilyl)acetate; Ethyl Trimethylsilylacetate.


1. Ager, D. J. OR 1990, 38, 1.
2. Grieco, P. A.; Wang, C.-L. J.; Burke, S. D. CC 1975, 537.
3. Sommer, L. H.; Gold, J. R.; Goldberg, G. M.; Marans, N. S. JACS 1949, 71, 1509.
4. Tsuge, O.; Kanemasa, S.; Suzuki, T.; Matsuda, K. BCJ 1986, 59, 2851.
5. Crimmin, M. J.; O'Hanlon, P. J.; Rogers, N. H. JCS(P1) 1985, 541.
6. Tajima, Y.; Yoshida, A.; Takeda, N.; Oida, S. TL 1985, 26, 673; Lucast, D. H.; Wemple, J. TL 1977, 1103.
7. Brook, A. G.; Anderson, D. G.; Duff, J. M. JACS 1968, 90, 3876.

David J. Ager

The NutraSweet Company, Mount Prospect, IL, USA



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