Table 2 Selective desilylation of phenolic silyl ethers in the presence of alcoholic silyl ethersa
Entry
1
Substrate
Product
Time/h
3
t (◦C)
rt
Yield/%b
93
2
3
4
5
4
3
3
4
rt
rt
rt
rt
92
94
98
99
a All reactions were carried out with 0.1 mmol of the substrate and 1.5 equiv KF in tetraethylene glycol (1.0 mL) at room temperature. b Isolated yields.
silyl ethers can be selectively cleaved in high yield in the presence
of certain acid- and base-labile functional groups. Moreover, the
phenolic silyl ethers were cleaved exclusively, without affecting
the alcoholic silyl ethers, at room temperature. The advantages of
this procedure over the previously reported processes include its
simplicity and the clean and rapid reactions it promotes. Therefore,
we believe that this protocol will find wide applications in the
synthesis of complex molecules.
Research Centers Program, MEST), 2011-0001334 (SRC program,
MEST), R31-2008-10029 (WCU program, MEST) and B551179-
10-03-00 (Cooperative R&D Program, Korea Research Council
Industrial Science and Technology).
Notes and references
1 P. G. M. Wuts and T. W. Greene, Greene’s Protecting Groups in Organic
Synthesis, 4th ed.; John Wiley & Sons, Hoboken, NJ, 2007.
2 B. C. Ranu, U. Jana and A. Majee, Tetrahedron Lett., 1999, 40, 1985–
1988 and references therein.
3 E. W. Collington, H. Finch and I. J. Smith, Tetrahedron Lett., 1985, 26,
681–684.
Experimental
General procedures for the desilylation reactions
4 (a) H. Yan, H. B. Jang, J. W. Lee, H. K. Kim, S. W. Lee, J. W. Yang and
C. E. Song, Angew. Chem., Int. Ed., 2010, 49, 8915–8917; (b) J. W. Lee,
H. Yan, H. B. Jang, H. K. Kim, S.-W. Park, S. Lee, D. Y. Chi and C. E.
Song, Angew. Chem., Int. Ed., 2009, 48, 7683–7686.
5 (a) J. H. Clark, Chem. Rev., 1980, 80, 429–752; (b) E. J. Corey and B. B.
Snider, J. Am. Chem. Soc., 1972, 94, 2549–2550.
6 S. V. Ankala and G. Fenteany, Tetrahedron Lett., 2002, 43, 4729–4732.
7 (a) B. Wang, H.-X. Sun and Z.-H. Sun, J. Org. Chem., 2009, 74, 1781–
1784; (b) Z.-Y. Jiang and Y.-G. Wang, Tetrahedron Lett., 2003, 44, 3859–
3861; (c) S. V. Ankala and G. Fenteany, Tetrahedron Lett., 2002, 43,
4729–4732; (d) R. D. Crouch, M. Stieff, J. L. Frie, A. B. Cadwallader
and D. C. Bevis, Tetrahedron Lett., 1999, 40, 3133–3136.
8 Deprotection protocols with the opposite “alkyl selectivity” are more
abundant, for representative recent examples, see: (a) S. T. A. Shah and
P. J. Giury, Org. Biomol. Chem., 2008, 6, 2168–2172; (b) A. T. Khan,
S. Ghosh and L. H. Choudhury, Eur. J. Org. Chem., 2004, 2198–2204;
(c) T. Oriyama, Y. Kobayashi and K. Noda, Synlett, 1998, 1047–1048;
(d) B. H. Lipshutz and J. Keith, Tetrahedron Lett., 1998, 39, 2495–2498;
(e) E. W. Collington, H. Finch and I. J. Smith, Tetrahedron Lett., 1985,
26, 681–684.
Spray dried potassium fluoride (8.7 mg, 0.15 mmol) and dried
tetraethylene glycol (1.0 mL) were added to a vial and stirred with a
magnetic stirring bar. The silyl protected substrate (0.1 mmol) was
then added and the reaction mixture stirred at room temperature
or 80 ◦C. The reaction was followed by TLC (EtOAc : hexanes =
1 : 4) until the starting materials were no longer detected.
After the reaction was completely finished, the reaction mixture
was quenched with water (10 mL) and extracted with diethyl
ether (10 mL X 3). The combined organic layer was dried over
anhydrous MgSO4, filtered and purified by short silica column
chromatography (EtOAc : hexane = 1 : 4) to afford the desilylated
alcohol product as a colorless oil or solid.
Acknowledgements
9 (a) T.-Y. Ku, T. Grieme, P. Raje, P. Sharma, S. A. King and H. E. Morton,
J. Am. Chem. Soc., 2002, 124, 4282–4286. For a general survey of silyl
migration, see: (b) ref. 1, pp 166–171 and references therein.
This work was supported by grants NRF-20090085824 (Basic
Science Research Program, MEST), NRF-2010-0029698 (Priority
This journal is
The Royal Society of Chemistry 2011
Org. Biomol. Chem., 2011, 9, 8119–8121 | 8121
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