applications with these reagents difficult. To explore the
possibility of repetitive use of both catalytic components,
several attempts to immobilize this catalytic system have
been made.4-6 Early attempts to immobilize OsO4 on solid-
supported alkaloid ligands failed due to severe osmium
leaching.4 Recently, Kobayashi reported that microencapsu-
lated OsO4 in a polymer matrix can be used as a recyclable
catalyst.5 However, high loading (5 mol %) of osmium is
needed to achieve a reasonable reaction rate. Very recently,
another approach to immobilize K2OsO4‚2H2O has been
achieved using an ion-exchange technique on various solid
supports.6 Although recycling experiments using 1 mol %
of this type of immobilized osmium catalyst have been
successfully performed for five consecutive reactions, the
amount of catalyst is still too large compared to that needed
in homogeneous AD reactions. In homogeneous cases, 0.2
mol % osmium is enough to complete most of the reactions.
In searching for a more efficient heterogeneous catalytic
system for AD reactions, we considered that OsO4 might be
simply immobilized onto nonionic porous resins such as
Amberlite XAD-4 (polystyrene-based) and XAD-7 (poly-
acrylate-based). Synthetic nonionic adsorbents such as
XAD-4 and XAD-7 are essentially highly cross-linked
macroporous resins bearing residual vinyl groups (from 0.20
to over 0.40 mol of vinyl groups per mole of polymer
repeating units).7 Thus, our idea was that OsO4 might be
simply anchored to residual vinyl groups within pores of the
resins by osmylation (Scheme 1) and freed from the solid
Scheme 1. Preparation of Solid Osmium Catalyst
Figure 1. XPS spectra of the XAD-7‚Os complex (a, before use;
b, recovered after reaction, entry 1 in Table 2).
The polymer-supported osmium catalysts were prepared
as follows. Amberlite XAD-4 or XAD-7 (9.50 g)8 was added
in t-BuOH/H2O (v/v ) 1:1, 95 mL) at room temperature,
and to this mixture was added 0.98 wt % of aqueous solution
of OsO4 (95 mL). The reaction mixture was stirred for 4 h
at room temperature. During the reaction of the resins with
OsO4, the solid turned black (XAD-4) or midnight blue
support in situ by an oxidant. After the desired reaction with
alkene is complete, the OsO4 is then taken up by other free
vinyl groups on the solid support and thereby immobilized
for reuse. Here we report our preliminary results.
(4) Reviews for solid-supported alkaloid ligands: (a) Song, C. E.; Lee,
S.-g. Chem. ReV. 2002, 102, 3495-3524. (b) Salvadori, P.; Pini, D.; Petri,
A.; Mandoli, A. In Chiral Catalyst Immobilization and Recycling; De Vos,
D. E., Vankelecom, I. F. J., Jacobs, P. A., Eds.; Wiley-VCH: Weinheim,
Germany, 2000; pp 235-246. (c) Salvadori, P.; Pini, D.; Petri, A. Synlett
1999, 1181-1190. (d) Bolm, C.; Gerlach, A. Eur. J. Org. Chem. 1998, 21,
21-27.
(3) For reviews: (a) Kolb, H. C.; Van Nieuwenhze, M. S.; Sharpless,
K. B. Chem. ReV. 1994, 94, 2483-2547. (b) Beller, M.; Sharpless, K. B.
In Applied Homogeneous Catalysis with Organometallic Compounds;
Cornils, B., Herrmann, W. A., Eds.; VCH Publishers: New York, 1996;
Vol. 2, pp 1009-1024. (c) Marko´, I. E.; Svendsen, J. Dihydroxylation of
Carbon-Carbon Double Bonds. In ComprehensiVe Asymmetric Catalysis
II; Jacobsen, E. N., Pfaltz, A., Yamamoto, H., Eds.; Springer-Verlag: Berlin,
1999; Vol. 2, pp 713-787. (d) Johnson, R. A.; Sharpless, K. B. Catalytic
Asymmetric Dihydroxylation-Discovery and Development. In Catalytic
Asymmetric Synthesis, 2nd ed.; Ojima, I., Ed.; Wiley-VCH: Weinheim,
Germany, 2000; pp 357-398. (e) Bolm, C.; Hildebrand, J. P.; Muniz, K.
Recent Advances in Asymmetric Dihydroxylation and Aminohydroxylation.
In Catalytic Asymmetric Synthesis, 2nd ed.; Ojima, I., Ed.; Wiley-VCH:
Weinheim, Germany, 2000; pp 399-428.
(5) (a) Nagayama, S.; Endo, M.; Kobayashi, S. J. Org. Chem. 1998, 63,
6094-6095. (b) Kobayashi, S.; Endo, M.; Nagayama, S. J. Am. Chem. Soc.
1999, 121, 11229-11230. (c) Kobayashi, S.; Ishida, T.; Akiyama, R. Org.
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(6) (a) Choudary, B. M.; Chowdari, N. S.; Kantam, M. L.; Raghavan,
K. V. J. Am. Chem. Soc. 2001, 123, 9220-9221. (b) Choudary, B. M.;
Chowdari, N. S.; Jyothi, K.; Kantam, M. L. J. Am. Chem. Soc. 2002, 124,
5341-5349.
(7) (a) Gao, J. P.; Morin, F. G.; Darling, G. D. Macromolecules 1993,
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(8) Resins were pretreated by Soxhlet extraction with methanol for several
days, followed by drying under vacuum.
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