Deprotection of Trimethylsilyl Ethers
1177
alcohols under solvent-free conditions in almost quantitative yields using a
conventional microwave oven and montmorillonite K-10 clay as solid support. The
deprotection reaction of the trimethylsilyl group was also carried out with
PdCl (PhCN)2 as the catalyst under microwave irradiation. An interesting
2
phenomenon with this complex is that the reaction works best if a drop of water
is added to the reaction mixture before heating in the microwave oven.
Interestingly enough, without addition of water the desilylation reaction did not
occur (Scheme 1). The protected phenols and alcohols are listed in Table 1.
In conclusion, the present study shows that deprotection of the trimethylsilyl
group in alcohols and phenols can successfully be performed in dry media
catalyzed by commercially available montmorillonite K-10 or by PdCl (PhCN) in
2
2
very short time and in almost quantitative yields.
Experimental
Activated montmorillonite K-10 clay was prepared by heating it in a commercial microwave oven
900 W) for ®ve minutes just before use as a solid support. All compounds were identi®ed by means
(
of their NMR and IR spectra.
Desilylation of phenols or alcohols in the presence of montmorillonite K-10 clay
3
mmol of silyl ether was placed in a 5 cm beaker, and 0.1 g of activated montmorillonite K-10 clay
1
3
was added. The beaker was placed in a 50 cm te¯on container and irradiated in a microwave oven
900 W) for 1 to 5 min. The progress of the reaction was monitored by GLC. After completion of the
reaction, the product was extracted with ether or CH Cl , ®ltered, and the solvent was evaporated
(
2
2
under reduced pressure to yield the corresponding phenol or alcohol.
Desilylation of phenols or alcohols in the presence of PdCl (PhCN)
2
2
3
1
mmol of silyl ether was placed in a 5 cm beaker, and 0.01 g of PdCl (PhCN) (1 mol%) was added.
2 2
3
Then one drop of water was added to the reaction mixture. The beaker was placed in a 50 cm te¯on
container and irradiated in a microwave oven (900 W) for 3 to 5 min. The progress of the reaction
was monitored by GLC. After completion of the reaction, the product was extracted with ether or
CH Cl , ®ltered, and the solvent was evaporated under reduced pressure to yield the corresponding
2
2
phenol and alcohol.
Acknowledgements
We thank the Iranian Scienti®c Research Council for ®nancial support of this work.
References
[
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[
[
[
[
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