[768-33-2]  · C8H11ClSi  · Chlorodimethylphenylsilane  · (MW 170.72)

(nucleophilic silylation;1 alcohol derivatization;2 antenna chromophore;3 enolate trapping;4 Kumada-Fleming-Tamao oxidation5)

Alternate Names: dimethylphenylsilyl chloride; DMPSCl.

Physical Data: bp 194-198 °C (63 °C/2 mmHg), d420 1.026 g cm-3; nD20 1.508.

Solubility: sol THF, ether, hexane.

Form Supplied in: liquid. Typical low-level impurities are metathesis products including dichloromethylphenylsilane (bp 205 °C).

Analysis of Reagent Purity: generally used as received. The methyl group appears at d 2.4 and the silicon atom at d 19.9 in the 1H and 29Si NMR spectra, respectively.6

Preparative Methods: widely available.

Handling, Storage, and Precautions: like other chlorosilanes, this compound can be destructive to tissue of the mucous membranes, upper respiratory tract, eyes and skin. Store in a cool dry place; the compound is moisture sensitive.

Chlorodimethylphenylsilane (DMPSCl) may be used in many of the same applications as chlorotrialkylsilanes, but in some cases the presence of the phenyl group on silicon offers advantages. For example, Me2PhSiLi is easier to prepare than Me3SiLi.7

Nucleophilic Silation using Dimethylphenylsilylmetallics.

Several dimethylphenylsilylmetallics have been prepared (see Table 1). The most useful reaction in the class is conjugate addition of the silylcuprates to a,b-unsaturated esters and enones (eq 1).1

Hydroxyl Derivatization.

Chlorodimethylphenylsilane is a useful derivatizing agent for alcohols.2 DMPSCl derivatized monosaccharides may be analyzed chromatographically with UV detection.14 A novel application of the UV-absorbing ability of the dimethylphenylsilyloxy chromophore uses 266 nm light absorbed by the DPS `antenna' in 3a-dimethylphenylsilyloxy-5a-androstane-11,17-dione for photolytic reduction of the C-17 keto group.3 Photolysis with 308 nm light absorbed by the ketone moieties produces predominately D-ring epimerization.

Other Nucleophilic Reactions at Silicon.

DMPSCl may be used to trap ester enolates4 (however, lactam enolates silylate at carbon).15 Numerous C-silylations of organolithium compounds with DMPSCl have been reported (eq 2).5,16 Other compounds derived from DMPSCl include the azide,17 tributylstannane,18 cyanide,19 isocyanate,20 and isoselenocyanate.21

Protodesilation/Oxidation (Kumada-Fleming-Tamao Oxidation).

Another advantage of the dimethylphenylsilyl group over trialkylsilyl is that the phenyl substituent may be readily removed by protodesilation.7 Kumada-Fleming-Tamao oxidation converts C-silyl compounds into alcohols. Allylic dimethylphenylsilanes are preferred substrates for conversion to the corresponding allylic alcohols,5 which is the basis for use of the b-silylethyl vinyl ketone (from 1) as a b-hydroxyethyl vinyl ketone synthon in the Robinson annulation reaction.

1. (a) Amberg, W.; Seebach, D. CB 1990, 123, 2439. (b) Ager, D. J.; Fleming, I.; Patel, S. K. JCS(P1) 1981, 2520. (c) Fleming, I.; Newton, T. W.; Roessler, F. JCS(P1) 1981, 2527.
2. Harvey, D. J. J. Chromatogr. 1978, 147, 291.
3. Wu, Z.Z.; Morrison, H. JACS 1992, 114, 4119.
4. Quirk, R. P.; Ren, J. Macromolecules, 1992, 25, 6612.
5. Kim, S.; Emeric, G.; Fuchs, P. L. JOC 1992, 57, 7362.
6. Chuy, N. D.; Chvalovsky, V.; Schraml, J.; Magi, M.; Lippmaa, E. CCC 1975, 40, 875.
7. Fleming, I.; Henning, R.; Plaut, H. CC 1984, 29.
8. Trost, B. M.; Tour, J. M. JOC 1989, 54, 484.
9. Fuerstner, A.; Weidmann, H. JOM 1988, 354, 15.
10. Chen, H.; Oliver, J. P. JOM 1986, 316, 255.
11. Sharma, S.; Oehlschlager, A. C. T 1989, 45, 557.
12. Morizawa, Y.; Oda, H.; Oshima, K.; Nozaki, H. TL 1984, 25, 1163.
13. Larson, G. L.; Rosario, O. JOM 1979, 168, 13.
14. (a) White, C. A.; Vass, S. W.; Kennedy, J. F.; Large, D. E. J. Chromatogr. 1983, 264, 99. (b) White, C. A.; Vass, S. W.; Kennedy, J. F.; Large, D. E. Carbohydr. Res. 1983, 119, 241.
15. Trost, B. M.; Kunz, B. A. JOC 1974, 39, 2475.
16. Reich, H. J. JOC 1975, 40, 2570.
17. Sukata, K. JOC 1988, 53, 4867.
18. Ritter, K. S 1989, 218.
19. (a) Sukata, K. BCJ 1987, 60, 2257. (b) Mai, K.; Patil, G. JOC 1986, 51, 3545.
20. Kozyukov, V. P.; Muzovskaya, E. V.; Mironov, V. F. ZOB 1983, 53(5), 1096.
21. Sukata, K. JOC 1989, 54, 2015.

Dallas K. Bates

Michigan Technological University, Houghton, MI, USA

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