Table 1 Ring opening results of epoxides (0.6 mmol) by using catalyst 3 in CH3OH at room temperature
Substrate
Time/h
Conversion yielda b (%)
Cyclohexene oxide
Cyclopentene oxide
Cyclooctene oxide
Z-Stilbene oxide
E-Stilbene oxide
2-Butene oxide
1c
5
> 99%
> 99%
39
> 99%
> 99%
> 99%
48d
10e
2e
3
Styrene oxide
1-Hexene oxide
1
3
> 99% (exclusively primary alcohol)
> 99% (primary : secondary = 56 : 44)
a See ESI† for detailed experimental procedures. All reactions were run at least three times, and the average conversion yields are presented. b Based
on the consumption of starting epoxide. c A mixture of CH2Cl2/MeOH (1 : 1) was used instead of MeOH due to insolubility. d The reaction was
carried out at 50 ЊC. e The moles of Z- and E-stilbene oxides were 0.2 mmol instead of 0.6 mmol.
Table 2 Hydrolysis of epoxides using catalyst 3 in a mixture of
efficient, mild, and easily recyclable method for the alcoholysis
and hydrolysis of epoxides. This result may also represent an
excellent starting point for the development of a new synthetic
method to produce metal complexes with labile solvent ligands
as recyclable catalysts for many important reactions such
as enantioselective solvolysis, hydrogenation, C–H bond oxid-
ation, and various environment-friendly oxidation reactions.
acetone/H2O (8 : 2 v/v) at room temperature
Substrate
Time/h
Conversion yielda (%)
Cyclohexene oxide
Cyclopentene oxide
Styrene oxide
2
32
48
> 99%
> 99%
> 99%
> 99%
1-Hexene oxide
120
a Same reaction conditions described in Table 1.
Acknowledgements
This work was supported by the Korean Science and Engineer-
ing Foundation through the Center for Molecular Catalysis at
Seoul National University, KOSEF grant 2000-1-12200-001-3
and KRF-2002-070-C00053. D.-W. Yoo is grateful for the
award of a BK21 fellowship.
(1)
Notes and references
could be easily recovered by a simple filtration and used repeat-
edly without any significant change from the original catalytic
activity even when used over 20 times consecutively. (Actually
all the reactions in Tables 1 and 2 were performed with the same
recycled catalyst.)
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P. J. Stang, Wiley-VCH, New York, 1998; (c) Transition Metals
for Organic Synthesis, ed. M. Beller and C. Bolm, Wiley-VCH,
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H. D. Verkruijsse, Springer, Berlin, 1998; (e) D. J. Gravert and
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Cyclopentene oxide was also completely converted within 5 h
and even cyclooctene oxide, which has been known as one of
the most difficult substrates for ring-opening reactions,10,11 was
ring-opened in moderate yield. Furthermore, this novel Fe()
mono(tpy) catalyst was also very active to acyclic epoxides.
E- and Z-Stilbene oxide, and Z-2-butene oxide were completely
converted to the corresponding products. All products were
determined to have E-stereochemistry by NMR, GC and GC/
MS analysis, comparing with authentic samples. Styrene oxide
was completely converted to 2-methoxy-2-phenyl ethanol
within 1 h and the alkoxy group was incorporated exclusively at
the benzylic position (α-carbon) instead of the less hindered
β-carbon center to generate a primary alcohol. In the case of
1-hexene oxide, however, a mixture of primary and secondary
alcohols (56 : 44) was obtained, showing no steric preference
for the alcoholic nucleophile. In addition, the reactions with
ethanol and propanol have shown similar product patterns as
with methanol, but the reaction rates were significantly slower
(more than 6 times). These results suggest that the regiochem-
istry of the ring opening by catalyst 3 would be dependent on
the electronic nature of the substrate rather than steric factors.
The more difficult reaction, hydrolysis, has also been carried
out with catalyst 3. Various epoxides could be completely con-
verted to the corresponding E-diols that were considered to be
valuable (chiral) building blocks for organic synthesis,12 even
though the reaction rate was slower than methanolysis as usual
(Table 2). Cyclohexene oxide was also found to be a superb
substrate for hydrolysis as shown for methanolysis and the
catalyst could be recycled with no observable loss in catalytic
activity or selectivity. Further detailed study on the reaction
mechanism of various solvolysis reactions with catalyst 3 is in
progress.
8 H. Egawa, T. Nonaka and K. Tsukamoto, Polym. J., 1990, 22,
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In conclusion, we have developed a novel synthetic method
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solid support surface. This catalyst system appears to be an
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3932
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