5
(a) G.-J. Brink, I. W. C. E. Arends and R. A. Sheldon,
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Hara, T. Mizugaki, K. Ebitani and K. Kaneda, J. Am. Chem.
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B. Solsona-Espriu, A. F. Carley, A. A. Herzing, M. Watanabe,
´
´
2
C. J. Kiely, D. W. Knight and G. J. Hutchings, Science,
2
006, 311, 362; (f) H. Tsunoyama, T. Tsukuda and H.
Sakurai, Chem. Lett., 2007, 36, 212; (g) Y. M. A. Yamada,
T. Arakawa, H. Hocke and Y. Uozumi, Angew. Chem., Int. Ed.,
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2007, 3862.
Scheme 2 Aerobic oxidation of alcohols in water open to air at room
temperature.
6
7
H. Miyamura, R. Matsubara, Y. Miyazaki and S. Kobayashi,
Angew. Chem., Int. Ed., 2007, 46, 4151.
See references in ref. 6.
In conclusion, we have developed novel gold–platinum
bimetallic cluster catalysts, which show high activity with
good substrate generality at room temperature without base
in aqueous media. Although catalytic turnover number and
turnover frequency are not the best compared to those of
previously reported catalysts, it should be noted that this is the
first example of oxidation of alcohols at room temperature
8 (a) M. Chen, D. Kumar, C.-W. Yi and D. A. Goodman,
Science, 2005, 310, 291; (b) J. Ahang, K. Sasaki, E. Sutter and
R. R. Adzic, Science, 2007, 315, 220; (c) A. M. Venezia,
V. L. Parola, V. Nicoli and G. J. Deganello, J. Catal., 2002, 212,
56; (d) R. W. J. Scott, O. M. Wilson, S.-K. Oh, E. A. Kenik and
R. M. Crooks, J. Am. Chem. Soc., 2004, 126, 15583;
(
e) N. Dimitratos, A. Villa, D. Wang, F. Porta, D. Su and
L. Prati, J. Catal., 2006, 244, 113; (f) J. K. Edwards, B. E. Solsona,
P. Landon, A. F. Carley, A. Herzing, C. J. Kiely and
G. J. Hutchings, J. Catal., 2005, 236, 69; (g) R. W. J. Scott,
C. Sivadinarayana, O. M. Wilson, Z. Yan, D. W. Goodman and R.
M. Crooks, J. Am. Chem. Soc., 2005, 127, 1380; (h) S. Zhou. K.
Mcllwrath, G. Jackson and B. Eichhorn, J. Am. Chem. Soc.,
2006, 128, 1780; (i) the reactivity of Au is also changed by
various impurities. See: Y. Iizuka, A. Kawamoto, K. Akita,
M. Date, S. Tsubota, M. Okumura and M. Haruta, Catal. Lett.,
1
3
without base using heterogeneous catalysts. Significantly the
selective oxidation of primary alcohols to the corresponding
aldehydes, which is difficult using pure gold catalysts, has been
5
f,6
realized.
The catalyst was recovered and reused several
times without loss of activity by simple operations. Further
investigations to apply these catalysts to other oxidation as
well as to clarify the precise mechanism of this oxidation
process are now in progress.
2
004, 97, 203; (j) D. Wang, A. Villa, F. Porta, D. Su and L.
Prati, Chem. Commun., 2006, 1956; (k) N. Kristian, Y. Yan and X.
Wang, Chem. Commun., 2008, 353.
S. Kobayashi and R. Akiyama, Chem. Commun., 2003, 449.
This work was partially supported by a Grant-in-Aid for
Scientific Research from Japan Society of the Promotion of
Science (JSPS). H. M. thanks the JSPS fellowship for Japanese
Junior Scientist. We are grateful to JEOL for analytical
support (STEM and EDS)
9
1
1
0 See Supplementary Information.
1 In case of oxidation of alcohols catalyzed by Au:PVP under basic
conditions, much larger KIE was observed. See: H. Tsunoyama, H.
Sakurai, Y. Negishi and T. Tsukuda, J. Am. Chem. Soc., 2005, 127,
9
374.
1
2 In course of oxidation reactions, both hydrogens are transferred
as protons mediated by a solvent, but to maintain neutrality
two electrons are transferred through metal clusters. This
type of mechanism was proposed for aerobic oxidations
catalyzed by metalloenzymes which also work at body
temperature open to atmosphere under neutral conditions in
aqueous solutions. See: G. A. Hamilton, Adv. Enzymol., 1969,
32, 55.
Notes and references
1
Comprehensive Organic Chemistry The Synthesis and Reactions of
Organic Compounds. ed. A. D. Barton and W. Ollis, Pergamon
Press, Oxford, 1979, vol. 1.
2
3
4
C. L. Hill, Advances in Oxygenated Processes, JAI Press, London,
vol. 1, 1988.
M. Hundlucky, Oxidations in Organic Chemistry, American
Chemical Society, Washington, DC, 1990.
T. Mallat and A. Baiker, Chem. Rev., 2004, 104, 3037.
13 This gold–platinum bimetallic catalyst shows high turnover
frequency at elevated temperature (TOF = 37 500/h for the
oxidation of sec-phenetyl alcohol at 160 1C).
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