ORGANIC
LETTERS
2002
Vol. 4, No. 26
4701-4704
A New, Simple, and Selective
Palladium-Catalyzed Cleavage of
Triethylsilyl Ethers
Delphine Rotulo-Sims and Joe1lle Prunet*
Laboratoire de Synthe`se Organique, UMR CNRS 7652, Ecole Polytechnique, DCSO,
F-91128 Palaiseau, France
Received October 18, 2002
ABSTRACT
A simple procedure for the cleavage of triethylsilyl (TES) ethers in the presence of 10 wt % Pd/C in methanol or 95% ethanol is reported. This
method allows selective removal of alkyl TES ethers in the presence of aromatic TES ethers or tert-butyldimethylsilyl (TBS) protecting groups.
As part of an ongoing project directed toward the total
synthesis of Dolabelides,1 we found that debenzylation of
compound 1 by hydrogenolysis with 10 wt % Pd/C in
absolute ethanol provided diol 2 and not the expected
monosilylated product (Scheme 1).
10% Pd/C in freshly distilled ethyl acetate to minimize
deprotection of the silyl ethers.5
This prompted us to further investigate our case of TES
ether deprotection using catalytic Pd/C in ethanol. We thus
found that TES ethers could be cleaved in the absence of
hydrogen but that a catalytic amount of Pd/C was required
to complete the reaction. Herein, we report the use of
catalytic Pd/C conditions to affect simple and selective
removal of TES ethers from alkyl derivatives without
deprotection of TBS groups. This paper encompasses the
scope and limitations of this method.
Scheme 1
Since first being reported in the early 1970s as protective
hydroxyl groups,6 silyl ethers have received a great deal of
attention and a large number of such silyl protective groups
are now available to the organic chemist. Among these, TES
ethers are very attractive. TES ethers are 10-100 times more
stable than TMS ethers and can withstand a much wider
range of reaction conditions,6b without being as hindered as
their TBS counterparts.
In fact, it has previously been reported in the literature
that primary and secondary silyl-protected alcohols such as
the TBS and DEIPS ethers could be cleaved using various
hydrogenolysis conditions [Pd(OH)2,2 wet Pd/C,3 catalytic
transfer hydrogenation4]. Smith et al. had also noticed, during
their synthesis of (+)-phyllanthoside, that it was necessary
to carefully monitor hydrogenolysis of the benzyl ethers using
To date, a great number of methods have been reported
for the cleavage of TES groups,7 most of them involving
acidic, basic, or oxidative conditions. Although selective
(1) (a) Grimaud, L.; de Mesmay, R.; Prunet, J. Org. Lett. 2002, 4, 419.
(b) Grimaud, L.; Rotulo, D.; Ros-Perez, R.; Guitry-Azam, L.; Prunet, J.
Tetrahedron Lett. 2002, 43, 7477.
(2) Toshima, K.; Yanagawa, K.; Mukaiyama, S.; Tatsuta, K. Tetrahedron
Lett. 1990, 31, 6697.
(3) Lee, K.; Wiemer, D. F. J. Org. Chem. 1993, 58, 7808.
(4) (a) Cormier, J. F. Tetrahedron Lett. 1991, 32, 187. (b) Cormier, J.
F.; Isaac, M. B.; Chen, L.-F. Tetrahedron Lett. 1993, 34, 243.
(5) Smith, A. B., III; Rivero, R. A.; Hale, K. J.; Vaccaro, H. A. J. Am.
Chem. Soc. 1991, 113, 2092.
(6) For a review on silyl protective groups, see: (a) Lalonde, M.; Chan,
T. H. Synthesis 1985, 817. (b) Greene, T. W.; Wuts, P. G. M. ProtectiVe
Groups in Organic Synthesis, 2nd ed.; Wiley: New York, 1991.
(7) For a review on selective silyl ethers deprotection, see: Nelson, T.
D.; Crouch, R. D. Synthesis 1996, 1031.
10.1021/ol0271382 CCC: $22.00 © 2002 American Chemical Society
Published on Web 12/04/2002