J. Legros, B. Crousse, D. Bonnet-Delpon, J.-P. B e´ gu e´
FULL PAPER
ence of a catalyst. Conversion rates measured after 4 h and Uncatalysed Epoxidation of Cycloctene with UHP. Typical Proced-
ure: UHP (282 mg, 3 mmol) was added to a well-stirred mixture of
2
4 h of reaction clearly show that ketone 4 (R ϭ C F ) is
8 17
cyclooctene (110 mg, 1 mmol) in HFIP (3 mL), at 25 °C. After 10 h
reaction was monitored by GC), the homogeneous mixture was
cooled to 0 °C, and tert-butyl methyl ether (3 mL) was added to
precipitate urea and unchanged UHP. The mixture was then filtered
through silica gel. Evaporation of the solvents afforded the pure
cyclooctene oxide (115 mg, 91%).
the most efficient catalyst, even more so than hexafluoro-
acetone. Similarly, the effect of the length of fluorinated
chain on the H O /fluoroketone catalysis was recently re-
ported.
for the efficient release of H O from UHP (entries 5, 7 and
(
2
2
[
18]
In this catalysed reaction, HFIP is still required
2
2
8
). It must be noted that ketone 4 has already been used
Epoxidation of Ethyl 10-Undecenoate with UHP Catalysed by Ke-
tone 4. Typical Procedure: UHP (113 mg, 1.2 mmol) was added to
a well-stirred mixture of ethyl 10-undecenoate (212 mg, 1 mmol)
and fluoroketone 4 hydrate (27 mg, 0.05 mmol) in HFIP (3 mL), at
successfully in the epoxidation of dodec-1-ene in HFIP,
with Oxone as primary oxidant.
The optimised reaction conditions, now requiring only
[21]
3Ϫ5 mol % of ketone 4, and 1.2 equiv. of UHP, have been
25 °C. After 48 h (reaction was monitored by GC), the homogen-
applied to the epoxidation of various olefins (Table 4).
eous mixture was cooled to 0 °C, and tert-butyl methyl ether (1 mL)
was added to precipitate urea and unchanged UHP. The mixture
was then filtered through silica gel. Evaporation of the solvents
afforded the pure ethyl 10-undecenoate oxide (203 mg, 89%).
Table 4. Catalysed epoxidation reaction with ketone 4 and UHP in
[
a]
HFIP
Acknowledgments
We thank Central Glass Co., Ltd for kindly providing dichlororo-
trifluoroacetone (2) and HFIP. We also thank the European Con-
tract of Research Training Network (‘‘Fluorous phase’’ HPRN CT
2000-00002) and the European Union (COST-Action ‘‘Fluorous
medium’’ D12/98/0012) for support.
[
[
1] [1a]
M. S. Cooper, H. Heaney, A. J. Newbold, W. R. Sanderson,
Synlett 1990, 533Ϫ535. [ H. Heaney, Aldrichimica Acta 1993,
1b]
[
a]
26, 35Ϫ45.
C. S. Lu, E. W. Hughes, P. A. Gigue
Reaction conditions: olefin (1 mmol), catalyst [ (0.03Ϫ
2]
`
re, J. Am. Chem. Soc. 1941,
b]
0
.05 mmol), UHP (1.2 mmol), HFIP (1 mL), 25Ϫ40 °C.
Yield
[
c]
63, 1507Ϫ1513.
of isolated product. Yield of monoepoxide (oxidation of trisub-
stituted double bond), 1:1 mixture of diastereoisomers.
[
[
3]
4]
K. Aida, J. Inorg. Nucl. Chem. 1963, 25, 165Ϫ170.
L. Astudillo, A. Galindo, A. G. Gonz a´ lez, H. Mansilla, Heter-
ocycles 1993, 36, 1075Ϫ1080.
[
[
5] [5a]
T. Schwenkreis, A. Berkessel, Tetrahedron Lett. 1993, 34,
Under these conditions, reactions proceeded faster than
in the absence of catalyst, and complete conversion of all
olefins, including the less reactive ones, was observed.
785Ϫ4788. [ E. Marcantoni, M. Petrini, O. Polimanti, Tetra-
5b]
4
hedron Lett. 1995, 36, 3561Ϫ3562.
6] [6a]
W. Adam, C. M. Mitchell, Angew. Chem. 1996, 108,
[
6b]
578Ϫ581; Angew. Chem. Int. Ed. Engl. 1996, 35, 533Ϫ535.
D. Sica, D. Musumeci, F. Zollo, S. De Marino, Eur. J. Org.
Chem. 2001, 3731Ϫ3739.
7] [7a]
Conclusion
[
[
[
K. S. Ravikumar, J. P. B e´ gu e´ , D. Bonnet-Delpon, Tetrahed-
ron Lett. 1998, 39, 3141Ϫ3144. [ K. S. Ravikumar, Y. M.
Zhang, J. P. B e´ gu e´ , D. Bonnet-Delpon, Eur. J. Org. Chem.
1998, 2937Ϫ2940.
7b]
This study demonstrates that the ability of HFIP to activ-
ate H O , combined with its ability to release H O from
2
2
2
2
8]
The KamletϪTaft solvent parameter α is defined as the hydro-
gen bond donating ability of a solvent: M. J. Kamlet, J. L. M.
Abboud, M. H. Abraham, R. W. Taft, J. Org. Chem. 1983,
its urea adduct, makes the UHP/HFIP system efficient and
safe for epoxidation under mild conditions. Epoxidation of
reactive olefins can be performed without any catalyst. It is
also possible to recover urea, unchanged UHP and HFIP.
For unreactive double bonds, catalysis is required and we
have shown that perfluorodecan-2-one 4, used in 3Ϫ5
mol % with 1.2 equiv. of UHP in HFIP, is an excellent cata-
lyst for complete conversion into oxiranes.
48, 2877Ϫ2887.
9]
For a r e´ sum e´ of physical constants of HFIP see: L. Eberson,
M. P. Hartshorn, O. Persson, F. Radner, Chem. Commun.
1996, 2105Ϫ2111.
K. Neimann, R. Neumann, Org. Lett. 2000, 2, 2861Ϫ2863.
M. C. A. van Vliet, I. W. C. E. Arends, R. A. Sheldon, Synlett
[
10]
[11]
2
001, 248Ϫ250.
[
[
12]
13]
Ionizing power Y is evaluated by ionization of 1-adamantyl
0 0
tosylate: Y ϭ log(k/k ), with k ϭ kinetic constant in 80%
aq. EtOH.
F. L. Schadt, T. W. Bentley, P. v. R. Schleyer, J. Am. Chem.
Soc. 1976, 98, 7667Ϫ7675.
When reaction is performed on a larger scale, HFIP can be
recovered by distillation.
For a recent review on catalytic oxidation reactions in the ab-
sence of metals see: W. Adam, C. R. Saha-Möller, P. A.
Ganeshpure, Chem. Rev. 2001, 101, 3499Ϫ3548.
Experimental Section
General: UHP (Aldrich), olefins (Aldrich or Fluka), catalysts 1 and
[14]
[15]
2
(Central Glass), catalyst 3 (Acros) and HFIP (Central Glass) were
used as received. Catalyst 4 was prepared according to the literat-
[
20]
ure. Gas chromatography was conducted with Hewlett Packard
4
890.
292
3
Eur. J. Org. Chem. 2002, 3290Ϫ3293