[4551-15-9]  · C9H14SSi  · (Phenylthio)trimethylsilane  · (MW 182.39)

(selective carbonyl protection;1,2 preparation of thioesters;3 cleavage of ethers4)

Physical Data: bp 93-99 °C/12 mmHg; d 0.967 g cm-3.

Solubility: sol organic solvents; incompatible with strong acids and strong oxidizing agents.

Preparative Method: commercially available, but can be prepared.5

Handling, Storage, and Precautions: moisture sensitive; use in a fume hood.


In the presence of an acid catalyst (Zinc Iodide, Aluminum Chloride, anhyd Hydrogen Chloride, Titanium(IV) Chloride), (phenylthio)trimethylsilane reacts with aldehydes and ketones at rt or below to form the corresponding thioacetals (eqs 1 and 2).1,2,6 With a,b-unsaturated aldehydes and ketones, initiation of the reaction with Potassium Cyanide-18-Crown-6 leads to exclusive formation of the 1,4-addition product (eq 3).1

Cleavage of Ethers.

Methyl and benzyl ethers can be readily cleaved under mild conditions (eq 4).4 The reagent also effects the stepwise and selective dealkylation of phosphotriesters.7

Miscellaneous Transformations.

(Phenylthio)trimethylsilane effects the direct conversion of glycosides into 1-thioglycosides,8,9 esters into thioesters,3 epoxides into b-(trimethylsilyloxy) thioethers and b-hydroxy ethers (eq 5),10 sulfoxides into sulfides,11 chalcone-derived acetals into a-alkoxy-a,b-unsaturated nitriles,12 and silyl enol ethers into vinyl sulfides (eq 6).13 The AlCl3-catalyzed reaction of (phenylthio)trimethylsilane with electrophilic cyclopropanes leads to the formation of ring-opened products (eq 7).14

1. Evans, D. A.; Truesdale, L. K.; Grimm, K. G.; Nesbitt, S. L. JACS 1977, 99, 5009.
2. Kusche, A.; Hoffmann, R.; Munster, I.; Keiner, P.; Bruckner, R. TL 1991, 32, 467.
3. Mukaiyama, T.; Takeda, T.; Atsumi, K. CL 1974, 187.
4. Hanessian, S.; Guindon, Y. TL 1980, 21, 2305.
5. Glass, R. M. JOM 1973, 61, 83.
6. Mori, I.; Bartlett, P. A.; Heathcock, C. H. JOC 1990, 55, 5966.
7. Takeuchi, Y.; Demachi, Y.; Yoshii, E. TL 1979, 20, 1231.
8. Hanessian, S.; Guindon, Y. Carbohydr. Res. 1980, 86, C3.
9. Nicolaou, K. C.; Daines, R. A.; Ogawa, Y.; Chakraborty, T. K. JACS 1988, 110, 4696.
10. Guindon, Y.; Young, R. N.; Frenette, R. SC 1981, 11, 391.
11. Numata, T.; Togo, H.; Oae, S. CL 1979, 329.
12. Soga, T.; Takenoshita, H.; Yamada, M.; Han, J. S.; Mukaiyama, T. BCJ 1991, 64, 1108.
13. Degl'Innocenti; Ulivi, P.; Capperucci, A.; Mordini, A.; Reginato, G.; Ricci, A. SL 1992, 499.
14. Dieter, R. K.; Pounds, S. JOC 1982, 47, 3174.

William C. Groutas

Wichita State University, KS, USA

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