Silicon(IV) Methoxide1

Si(OMe)4

[681-84-5]  · C4H12O4Si  · Silicon(IV) Methoxide  · (MW 152.25)

(methanol synthon in aprotic media2)

Alternate Names: tetramethyl orthosilicate; tetramethoxysilane.

Physical Data: bp 121-122 °C; mp 4-5 °C; d 1.032 g cm-3; n20D 1.3688.

Solubility: sol common organic solvents.

Form Supplied in: commercially available as a colorless liquid.

Analysis of Reagent Purity: 1H NMR.

Purification: by distillation.

Handling, Storage, and Precautions: can be stored in a glass bottle but must be protected from moisture. Can cause blindness; special eye protection is required.

Acetal Synthesis.2

Acetalization of carbonyl compounds can be achieved by using an alkoxysilane and a catalytic amount (10 mol %) of Iodotrimethylsilane (eqs 1 and 2). Silicon(IV) methoxide is convenient for use in these reactions because silicon(IV) can be readily removed from the reaction mixture as a siloxane polymer after hydrolysis.

In a related reaction, 1,2-bis(trimethylsiloxy)ethane can be used for the formation of cyclic acetals (eq 3). Ketones react with alkyl silyl ethers in the presence of a catalytic amount of Trimethylsilyl Trifluoromethanesulfonate to give the corresponding acetals; cyclohex-2-enone forms the acetal without double bond migration.3

Synthesis of Homoallyl Ethers.

Treatment of a mixture of an aldehyde, silicon(IV) methoxide, and Allyltrimethylsilane gives homoallyl ethers exclusively (eqs 4 and 5).4


1. Fieser, M. FF 1986, 12, 260.
2. Sakurai, H.; Sasaki, K.; Hayashi, J.; Hosomi, A. JOC 1984, 49, 2808.
3. Tsunoda, T.; Suzuki, M.; Noyori, R. TL 1980, 1357.
4. Sakurai, H.; Sasaki, K.; Hosomi, A. TL 1981, 22, 745.

Hideki Sakurai

Tohoku University, Sendai, Japan



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