2422
H. Zhang et al. / Tetrahedron: Asymmetry 16 (2005) 2417–2423
À1
was removed. To this dark solid, 30 mL of CH Cl was
2
in the region of 4000–400 cm . The samples of
2
added, and the organic phase washed with 15 mL of dis-
tilled water. The water samples were detected by HNO3–
AgNO solution until no characteristic white floc was
Mn(salen)Cl, Mn(salen)OPh and polymer-immobilized
Mn(salen) catalysts were prepared as KBr pellets and
measured under ambient conditions (20 ꢁC). The UV–
vis spectra were recorded on a JASCO V-550 spectro-
meter under ambient conditions (20 ꢁC) in the wave-
length range of 190–800 nm with a band width of
5 nm. The solution of Mn(salen-a)Cl in CH Cl with a
3
observed (needed about three times). Then the CH Cl
2
2
solution was washed with 10 mL of saturated NaCl
solution and dried over anhydrous Na SO . Removing
CH Cl gave brown-dark solid Mn(salen-a, or b)OPh
2
4
2
2
2
2
À1
complexes. Mn(salen-a)OPh: IR (KBr, cm ): m =
955, 1612, 1535, 1477, 1312, 1253, 1175, 837; Elemental
analysis calcd (%) for C H MnN O : C, 73.26; H,
concentration of about 1.0 mM was prepared and put
into a 1 cm quartz cell for UV–vis adsorption with
CH Cl as reference. Diffuse reflectance UV–vis spectra
2
4
2
57
2
3
2
2
8
.28; N, 1.16. Found: C, 74.09; H, 8.37; N, 1.04. Mn-
of the solid polymer samples were recorded in the
spectrophotometer with an integrating sphere using
BaSO as reference.
À1
(
salen-b)OPh: IR (KBr, cm ): m = 2956, 1614, 1533,
1252, 1174, 836, 699; Elemental analysis calcd (%) for
C H MnN O : C, 75.95; H, 7.47; N, 1.01. Found: C,
4
5
0
59
2
3
7
6.81; H, 7.79; N, 1.30.
4.6. Asymmetric epoxidation reactions
4
.3. Immobilizing Mn(salen) catalyst by phenoxyl group
The racemic epoxides samples were synthesized by epox-
idation of the corresponding olefins with m-CPBA in
Polystyrene (short for PS, 5.4 g) was added to ethanol
180 mL) containing concentrated sulfuric acid (3.44 g)
and catalyst FeCl Æ6H O (132 mg) and this suspension
CHCl at 0 ꢁC and confirmed by GC–MS analysis. A
3
(
typical epoxidation procedure is shown as follows. A
solution of olefins (1 mmol) in CH Cl (3 mL) contain-
3
2
2
2
1
9
stirred for 30 min at 50 ꢁC. Then H O (13.2 mL)
ing n-nonane (internal standard, 1.0 mmol), PPNO
(0.38 mmol, if necessary) and homogeneous (1.5 mol %)
or heterogeneous catalysts (0.5–1.5 mol %, based on
the Mn amount in the catalysts) was kept at either 0
or 20 ꢁC. NaClO aqueous solution (pH 11.5, 0.55 M,
3.64 mL) was added and this heterogeneous system
was then stirred for either 6 h or 24 h. After reaction,
the organic layer was concentrated and purified by flash
chromatography to remove homogeneous catalysts or
filtrated to remove heterogeneous catalysts. The yields
and ee values of the epoxides were determined by GC.
The solid catalysts were filtrated and washed thoroughly
with distilled water and ethanol followed by dichloro-
methane and used for the next cycle.
2
2
was added to the mixture in four equal portions and
the mixture stirred for an additional 20 h (Scheme 3a).
The solid was filtrated and washed with ethanol and dis-
tilled water until neutrality to give PS–PhOH. To this
resulting PS–PhOH powder, 180 mL of distilled water
and 20 mL ethanol containing NaOH (216 mg) was
added and this mixture stirred for 3 h at room tempera-
ture. The solid was filtrated and washed with distilled
water until pH 7 to give PS–PhONa as white powder.
A mixture of Mn(salen)Cl (1.0 mmol) and PS–PhONa
(
2.0 g) was added to ethanol (60 mL) and this suspension
was stirred for 5 h under reflux. The mixture was then fil-
trated, washed thoroughly with ethanol and CH Cl to
2
2
produce PS–PhOMn(salen) as little yellow powder.
The CH Cl filtrate was detected by UV–vis until no
peaks could be detected (with CH Cl as reference).
2
2
2
2
Acknowledgements
4.4. Immobilizing Mn(salen) catalysts by phenyl sulfonic
group
Financial support from the National Natural Science
Foundation of China (NSFC, Grant No. 20321303) is
gratefully acknowledged. We would also like to thank
Dr. Jianliang Xiao at University of Liverpool, UK, for
helpful discussions.
To this brown powder sulfonic acid modified polystyr-
ene (short for PS–PhSO H, 2.87 g, 10 mmol H )
was added distilled water (100 mL) containing NaOH
+
3
(
room temperature (Scheme 3b). The solid was filtrated
400 mg, 10 mmol) and this mixture stirred for 4 h at
References
and washed to neutral to produce PS–PhSO Na as a
3
1
7
brown powder. The mixture of Mn(salen)Cl (1.0
mmol) and PS–PhSO Na (1.0 g) were added to ethanol
1
. (a) Zhang, W.; Loebach, J. L.; Wilson, S. R.; Jacobsen, E.
N. J. Am. Chem. Soc. 1990, 112, 2801–2803; (b) Irie, R.;
Noda, K.; Ito, Y.; Matsumoto, N.; Katsuki, T. Tetra-
hedron Lett. 1990, 31, 7345–7348.
2. (a) Bianchini, C.; Barbaro, P. Top. Catal. 2002, 19, 17–32;
b) Fan, Q. H.; Li, Y. M.; Chan, A. S. C. Chem. Rev. 2002,
3
(
60 mL) and this suspension stirred for 5 h under reflux.
After the solid was filtrated and washed thoroughly with
ethanol and CH Cl , PS–PhSO Mn(salen) was obtained
as brown powder. The CH Cl filtrate was analyzed by
2
2
3
(
1
2
2
2
02, 3385–3466; (c) Song, C.-E.; Lee, S.-G. Chem. Rev.
002, 102, 3495–3524; (d) McMorn, P.; Hutchings, G. J.
Chem. Soc. Rev. 2004, 33, 108–122; (e) Li, C. Catal. Rev.-
Sci. Eng. 2004, 46, 419–492.
UV–vis until no peaks could be detected from the
spectra (with CH Cl as reference).
2
2
4
.5. Characterization
3
. Blaser, H. U.; Pugin, B. In Chiral Reactions in Hetero-
geneous Catalysis; Jannes, G., Dubois, V., Eds.; Plenum
Press: New York, 1995, p 33.
4. (a) Srinivasan, K.; Michaud, P.; Kochi, J. K. J. Am. Chem.
Soc. 1986, 108, 2309–2320; (b) Canali, L.; Cowan, E.;
The measurements of the IR spectra were performed on
a Fourier transform infrared spectrometer (Nicolet
Nexus 470) with a resolution of 4 cm and 64 scans
À1
Zhang, Huidong
