3-Chloro-2-trimethylsilyloxy-1-propene1

[76634-95-2]  · C6H13ClOSi  · 3-Chloro-2-trimethylsilyloxy-1-propene  · (MW 164.71)

(used for silyl enol ether synthesis;2 electrophilic acetonylation reagent3)

Physical Data: 61-63 °C/35-37 mmHg.

Solubility: sol common organic solvents but avoid hydroxylic solvents.

Analysis of Reagent Purity: 1H NMR.

Preparative Methods: a mixture of 16.5 g (0.10 mol) of 3-chloro-1-(trimethylsilyl)propan-2-one and 454 mg (1.0 mmol) of mercury(II) iodide was heated at 75-85 °C for 72 h. The mixture was distilled to give 13 g of 3-chloro-2-trimethylsilyloxy-1-propene.2 Alternatively, isomerization of 3-chloro-1-(trimethylsilyl)propan-2-one with Tetrakis(triphenylphosphine)nickel(0) gave the product in 90% yield.3

Purification: by distillation.

Handling, Storage, and Precautions: can be stored in a glass bottle under nitrogen. The reagent must be protected from moisture. The reagent should be handled in a well-ventilated hood and contact with the skin and eyes should be avoided.

Synthesis of Silyl Enol Ethers via Alkylation Reactions.

Alkylation and arylation of 3-chloro-2-trimethylsilyloxy-1-propene with lithium dialkyl- and diarylcuprate, respectively, gives silyl enol ethers in a regiospecific manner (eq 1).2

Electrophilic Acetonyl Equivalent.4

a-Metalated imines, hydrazones, and activated methylene compounds are acetonylated with 3-chloro-2-trimethylsilyloxy-1-propene in high yield (eq 2).

Highly regioselective acetonylation at either the tertiary or secondary a-carbon of 2-methylcyclohexanone can be achieved by selecting the optimal nitrogen substituent (eqs 3-5).

Formation of Imino Ketones.

Reaction of the title reagent with N-acetoxyaminoquinazolone gave the corresponding chloro ketone, which was converted to an imino ketone (eq 6).5

Reaction with Transition Metal Complexes.

3-Chloro-2-trimethylsilyloxy-1-propene can be a precursor of oxyallyl cations or a formal analog of trimethylenemethane. The reaction with Nonacarbonyldiiron gives the (oxodimethylidenemethane)iron dimer [(MeCOMe)(CO)3Fe]2.6 A similar (h3-2-trimethylsiloxyallyl)Fe(CO)2NO complex was also prepared.7 Os, Ir, and Pt carbonyls gave the corresponding metallacyclobutan-3-ones.2a

Cycloaddition.

The reaction of an analog, 3-bromo-3-methyl-2-trimethylsiloxy-1-butene, with 1,3-dienes in dichloromethane in the presence of Zinc Chloride gave cycloheptenones as [3 + 4] cycloaddition products in good to excellent yields (eqs 7 and 8).8 Styrene derivatives give [3 + 2] cycloadducts as major products. For example, 2-(p-methylphenyl)-1-propene affords an aromatic sesquiterpene, a-cupranone, and its regiosomer (eq 9).


1. Fieser, M. FF 1982, 10, 286.
2. Sakurai, H.; Shirahata, A.; Araki, Y.; Hosomi, A. TL 1980, 21, 2325.
3. (a) Jones, M. D.; Kemmitt, R. D. W.; Fawcett, J.; Russell, D. R. CC 1986, 427. (b) Jones, M. D.; Kemmitt, D. W. Appl. Organomet. Chem. 1987, 1, 281.
4. Hosomi, A.; Shirahata, A.; Araki, Y.; Sakurai, H. JOC 1981, 46, 4631.
5. (a) Atkinson, R. S.; Kelly, B. J.; Williams, J. CC 1992, 373. (b) T 1992, 36, 7713.
6. (a) Frey, M.; Jenny, T. A. JOM 1991, 421, 257. (b) Frey, M.; Jenny, T. A.; Stoeckli-Evans, H. OM 1990, 9, 1806.
7. Itoh, K.; Nakanishi, S.; Otsuji, Y. BCJ 1991, 64, 2965.
8. Sakurai, H.; Shirahata, A.; Hosomi, A. AG(E) 1979, 18, 163.

Hideki Sakurai

Tohoku University, Sendai, Japan



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