490
B. Betzemeier et al.
LETTER
epoxide was observed but instead the corresponding
trans-diols 3k and 3l in respectively 63 % and 68 % yield
(Scheme 2).
60 % H2O2 (2.0 equiv), 1 (5 mol%)
OH
OH
C8F17Br / benzene
70 °C, 12 h
2k
3k: 63 %
In summary, we have described an efficient selenium cat-
alyzed epoxidation of alkenes in a fluorous biphase sys-
tem. The toxic selenium catalyst can be immobilized in
perfluorinated solvents which allows the facile separation
from the reaction mixture and its reuse for further reaction
runs.
OH
60 % H2O2 (2.0 equiv), 1 (5 mol%)
C8F17Br / benzene
70 °C, 12 h
OH
2l
3l: 68 %
Scheme 2
Other applications of the selenium catalyst in oxidation
chemistry are currently investigated in our laboratory.
The selenium catalyst 1 is readily prepared in three steps
starting from 2,4 diiodoaniline (4). Ullmann-type reaction
with iodoperfluorooctane in DMSO in the presence of
copper powder (120 °C, 1 h) afforded the doubly perfluo-
Acknowledgement
We thank the Deutsche Forschungsgemeinschaft (SFB 260,
roalkylated product 5 in 79 % yield.6 Sandmeyer-reaction Schwerpunktprogramm "Peroxidchemie" and Leibniz-Programm)
and the Fonds der Chemischen Industrie for generous financial sup-
port. F. L. thanks the Alexander von Humboldt Foundation for a fel-
lowship. We thank the companies BASF AG (Ludwigshafen),
Bayer AG (Leverkusen), ELF-Atochem S. A. (Pierre-Benite, Fran-
(i. NaNO2, HBr; ii. CuBr, HBr) yielded the corresponding
aryl bromide 6 in 60 % yield. After substitution with lith-
ium butylselenide in THF at -78 °C to 25 °C the aryl bu-
tylselenide 1 was obtained in 76 % yield (Scheme 3).7
ce) and Chemetall GmbH (Frankfurt) for the generous gift of che-
micals.
NH2
NH2
C8F17
I
1) NaNO2, HBr
2) CuBr, HBr
C8F17I, Cu
References and Notes
DMSO, 120 °C
(1) (a) Sharpless, K. B.; Young, M. W. J. Org. Chem. 1975, 40,
947; (b) Hori, T.; Sharpless K. B. J. Org. Chem. 1978, 43,
1689; (c) Kuwajima, I.; Shimizu, M.; Urabe, H. J. Org. Chem.
1982, 47, 837; (d) Grieco, P. A.; Yokoyama, Y.; Gilman, S.;
Nishizawa, M. J. Org. Chem. 1977, 42, 2034; (e) Syper, L.
Synthesis 1989, 167.
C8F17
I
4
5: 79 %
Br
SeBu
C8F17
C8F17
BuSeLi, THF
(2) Taylor, R. T.; Flood, L. A. J. Org. Chem. 1983, 48, 5160.
(3) (a) Horvárth, I. T.; Rábai, J. Science 1994, 266, 72; (b) Curran,
D. P. Chemtracts Org. Chem. 1996, 9, 75; (c) Cornils, B. An-
gew. Chem. Int. Ed. Engl. 1997, 36, 2057.
-80 °C to 25 °C, 2h
C8F17
C8F17
1: 76 %
6: 60 %
(4) (a) Klement, I.; Lütjens, H.; Knochel, P. Angew. Chem. Int.
Ed. Engl. 1997, 36, 1496; (b) Pozzi, G.; Banfi, S.; Manfredi,
A.; Montanari, F.; Quici, S. Tetrahedron 1996, 52, 11879;
(c) Pozzi, G.; Cinato, F.; Montanari, F.; Quici, S. J. Chem.
Soc. Chem. Commun. 1998, 877; (d) Betzemeier, B.; Lhermit-
te, F.; Knochel, P. Tetrahedron Lett. 1998, 39, 6667.
(5) The use of other perfluorinated solvents such as perfluoro-
hexane and perfluorodecaline led to similar results. Benzene
has been used as organic reaction medium since toluene is oxi-
dized under the reaction conditions.
Scheme 3
19
The leaching of the catalyst was followed by F-NMR.
Thus the reaction has been carried out in the presence of
fluorobenzene as internal standard under the conditions
described above. After separation of the two phases the
19F-NMR spectrum of the organic phase indicated that
only 0.1 % of the catalyst has been moved to the benzene
phase which demonstrates its excellent solubility in fluor-
inated solvents. The catalyst can be reused more than ten
times without decrease in yield nor increase in reaction
time. In the case of the epoxidation of cyclooctene (2a)
the reaction was repeated ten times with the same catalyst
solution leading to cyclooctene oxide (3a) in 90 - 93 %
yield within 1 h. Only in the first run a longer reaction
time was required because of the initial formation of the
catalyst (Table 2).8
(6) Yoshino, N.; Kitamura, M.; Seto, T.; Shibata, Y. Abe, M.;
Ogino, K. Bull. Chem. Soc. Jpn. 1992, 65, 2141.
(7) Analytical data for C26H12F34Se (1): 1H-NMR (300 MHz,
THF-d8): d 7.88 (d, J = 6.9 Hz, 1H), 7.74 (m, 2H), 3.13 (t, J =
7.5 Hz, 2H), 1.74 (quint, J = 6.9 Hz, 2H), 1.48 (sext, J = 7.5
Hz, 2H), 0.94 (t, J = 7.3 Hz, 3H); 13C-NMR (75 MHz, THF-
d8): d 141.9, 133.0, 131.2 (m), 129.4 (t, J = 24.6 Hz), 128.7
(m), 127.0 (t, J = 24.8 Hz), 120.3 - 109.5 (m, 16C), 32.1, 27.9,
24.0, 13.9; MS (EI, 70 eV): 1049 (M+, 20%); MA
(C26H12F34Se) calcd. C 29.76, H 1.15; Found C 29.75, H 1.39.
Synlett 1999, No. 4, 489–491 ISSN 0936-5214 © Thieme Stuttgart · New York