[420-56-4]  · C3H9FSi  · Fluorotrimethylsilane  · (MW 92.21)

(capable of silylating ketones, alcohols, and terminal alkynes3,4)

Alternate Name: TMSF.

Physical Data: bp 19 °C/730 mmHg.1

Solubility: sol most organic solvents.

Preparative Methods: from Chlorotrimethylsilane (TMSCl) by direct treatment with Hydrofluoric Acid.1,2 TMSF can also be generated in situ by reaction of Ethyl Trimethylsilylacetate (ETSA) and Tetra-n-butylammonium Fluoride (TBAF).3

Handling, Storage, and Precautions: typically generated in situ or used as prepared.

Ketones, alcohols, and terminal alkynes can be silylated in excellent yields using TMSF that has been generated in situ from ETSA and catalytic TBAF (eq 1).3,4 Ketones silylated in this manner often show high regioselectivity as compared to those silylated with TMSCl.3

Addition of an aldehyde or N-Bromosuccinimide to the crude reaction mixture also afforded an aldol3,4 or brominated product in good yield (eqs 2 and 3).3

Carbonyl compounds possessing no acidic a-protons undergo a Reformatsky-type reaction under ETSA-TBAF conditions to afford b-siloxy esters which can then be hydrolyzed to b-hydroxy esters (eq 4).3

Related Reagents.

Trimethylsilyl Nonaflate.

1. Marans, N. S.; Sommer, L. H.; Whitmore, F. C. JACS 1951, 73, 5127.
2. Eaborn, C. JCS 1952, 2846.
3. Nakamura, E.; Murofushi, T.; Shimizu, M.; Kuwajima, I. JACS 1976, 98, 2346.
4. Nakamura, E.; Shimizu, M.; Kuwajima, I.; Sakata, J.; Yokoyama, K.; Noyori, R. JOC 1983, 48, 932.

Nicholas J. Sisti

SmithKline Beecham Pharmaceuticals, King of Prussia, PA, USA

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