Z. Yan, W. Tian / Tetrahedron Letters 45 (2004) 2211–2213
2213
Table 2 (continued)
Entry
Substrate
Time (min)
2400
Product
Yield (%)b
O
9
53e
19
20
a Substrate:Rf SO2F:H2O2:OHꢀ ¼ 1:4:8:8 (equiv).
b Isolated yields.
c Trace of 5(6),16(17)bis-epoxide of 19 was also found in this reaction.
d a:b Isomer ¼ 2.2:1.
e a:b Isomer ¼ 1:1.
idation of trans-olefins (entries 2–4). In the case of 11
(entry 5), two isolated electron rich double bonds were
both epoxidized simultaneously. It was reported that the
epoxidation of 15 using peracetic acid as oxidant pro-
vided 16 in 94% yield after 17 h.6 For comparison, the
same reaction employing our present method occurred
with the formation of 16 in nearly quantitative yield
within only 10 min (entry 7). On the other hand,
although 4 N NaOH aqueous solution was used as base
in the reaction, ester group in substrates 13 and 17
(entries 6and 8) was not hydrolyzed under this condi-
tions even after leaving the reaction mixture stirred for
an additional 24 h. Furthermore, no formation of Bae-
yer–Villiger oxidation products was observed for sub-
strates bearing ketone group (entries 6–8). In entry 6, the
reaction selectivity between 5(6) and 16(17) double
bonds has further proved that true epoxidation reagent
is persulfonic acid generated from polyfluoro-
alkanesulfonyl fluorides and H2O2 rather than H2O2
itself. Finally for the highly sterically hindered olefin,
such as substrate 19 (entry 9), a moderate isolated yield
(53%) of product was still acquired by increasing reac-
tion time to 48 h along with the recovery of 44% of
starting material.
HCF2CF2OCF2CF2SO2F and 0.30 mL (3.00 mmol) of
30% H2O2 aqueous solution at room temperature. An
aqueous solution of 4 N NaOH (0.75 mL, 3.00 mmol)
was slowly added to the above obtained solution over a
period of 5–10 min. The resulting mixture was stirred for
an additional 10 min at room temperature. Crude
product obtained after usual work-up procedure was
further purified through flash chromatography affording
108 mg of corresponding epoxide 2 (yield 95%).
References and notes
1. (a) Schulz, M.; Kluge, R.; Lipke, M. Synlett 1993, 915–918;
(b) Kluge, R.; Schulz, M.; Liebsch, S. Tetrahedron 1996, 52,
2957–2976.
2. Oae, S.; Takata, T. Tetrahedron Lett. 1980, 21, 3689–3692.
3. Nielsen, A. T.; Atkins, R. L.; Norris, W. P.; Coon, C. L.;
Sitzmann, M. E. J. Org. Chem. 1980, 45, 2341–2347.
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Streitweieser, A.; Wilkins, C. L.; Kiehlmann, E. J. Am.
Chem. Soc. 1968, 90, 1598–1601; (c) Su, T. M.; Sliwinski,
W. F.; Schleyer, P. R. J. Am. Chem. Soc. 1969, 91, 5386–
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1982, 40, 337–352; (f) Bennua-Skalmowski, B.; Vorbrug-
gen, V. Tetrahedron Lett. 1995, 36, 2611–2614; (g) Chen, Q.
Y. J. Fluorine Chem. 1995, 72, 241–246.
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37, 8553–8556; (b) Zhu, Z.; Tian, W. S.; Liao, Q. J.; Wu, Y.
K. Bioorg. Med. Chem. Lett. 1998, 8, 1949–1952; (c) Fei, X.
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In conclusion, we have developed a novel oxidation
system Rf SO2F/H2O2/NaOH for the epoxidation of a
variety of electron rich olefins. The corresponding per-
sulfonic acid was generated in situ in the reaction and
acted as the oxidizing species in the epoxidation of
olefins. High efficiency and mild reaction conditions are
the main advantages for this novel oxidation system,
particularly suitable for the epoxidation of acid-sensitive
olefins. Therefore, it is recommended as an alternative
oxidation method in synthetic organic chemistry.
A typical experimental procedure is as follows: To
a stirred solution of 107 mg (0.37 mmol) of 1 in 10 mL
of MeOH were added 0.28 mL (1.50 mmol) of
6. Campbell, M. M.; Craig, R. C.; Boyd, A. C.; Gilbert, I. M.;
Logan, R. T.; Redpath, J.; Roy, R. G.; Savage, D. S.;
Sleigh, T. J. Chem. Soc., Perkin Trans. 1 1979, 2235–2247.