Chemistry Letters Vol.34, No.12 (2005)
1591
Table 3. Reuse of [Cu(bpy)(BF4)2(H2O)2(bpy)]n catalyst
Table 2. [Cu(bpy)(BF4)2(H2O)2(bpy)]n-catalyzed synthesis of
various ꢀ-hydroxy ketones
O2
[Cu(bpy)(BF4)2(H2O)2(bpy)]n (10 mol %)a
O2
Me3SiO
2
1
[Cu(bpy)(BF4)2(H2O)2(bpy)]n
O
R2
EtOH-H2O, 0 °C, 4.5 h
R1
OH
R1
EtOH-H2O, 0 °C
Runb
Yield/%c
Recovery of catalyst/%
R2 R3
R3
1
2
3
4
5
85
82
82
80
80
98
96
95
95
94
Catalyst
Amount
(mol %)a
Entry
Time/h
Yield/%b
Substrate
1
2
10
1
4.5
24
85
74
1
aCatalyst amount is based on the monomeric structure.
bCatalyst was recovered by centrifugation (3000 rpm for
3 min in 3 times each) after treatment with P(OEt)3. cIsolated
yield.
Me3SiO
Et
Pr
(4)
(5)
(6)
(7)
3
4
5
6
10
10
10
10
5
5
81
84
72
32
Me3SiO
This work was supported by a Grant-in-Aid for Scientific
Research from the Ministry of Education, Culture, Sports,
Science and Technology of the Japanese Government, and by
a grant from the Graduate School of Science and Technology,
Chiba University.
Me3SiO
24
4
References
1
Recent reviews of the synthesis of ꢀ-hydroxy kenones: A. B.
Jones, in ‘‘Comprehensive Organic Synthesis,’’ ed. by B. M.
Trost and I. Fleming, Pergamon, Oxford (1991), Vol. 7,
p 151.
Recent progresses on the synthesis of ꢀ-hydroxy kenones:
a) H. Yamamoto, M. Tsuda, S. Sakaguchi, and Y. Ishii,
´
J. Org. Chem., 62, 7174 (1997). b) A. Solladie-Cavallo, P.
Lupattelli, L. Jierry, P. Bovicelli, F. Angeli, R. Antonioletti,
and A. Klein, Tetrahedron Lett., 44, 6523 (2003). c) H.
Me3SiO
Me3SiO
2
7
8
(8)
(9)
5
10
10
68
60
Me
Me3SiO
Bn
´
Sunden, M. Engqvist, J. Casas, I. Ibrahem, and A. Cordova,
Angew. Chem., Int. Ed., 43, 6532 (2004).
´
13
3
4
a) T. V. Lee and J. Toczek, Tetrahedron Lett., 23, 2917
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The addition of BHT as a radical inhibitor didn’t affect the
catalysis.
Me3SiO
Me
Me
(10)
9
10
10
24
18
79
62
OMe
Me3SiO
10
(11)
Me
5
6
7
aCatalyst amount is based on the monomeric structure. bIsolated
yield after treatment with P(OEt)3.
J. N. Gardner, F. E. Carlton, and O. Gnoj, J. Org. Chem., 33,
3294 (1968).
p-methoxyacetophenone (30%).
Recent progress on the applications of organic–inorganic
hybrid polymer to the organic synthesis: a) C. Bianchini,
E. Farnetti, M. Graziani, J. Kaspar, and F. Vizza, J. Am.
Chem. Soc., 115, 1753 (1993). b) M. Fujita, Y. J. Kwon, S.
Washizu, and K. Ogura, J. Am. Chem. Soc., 116, 1151
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Y. J. Jeon, and K. Kim, Nature, 404, 982 (2000). d) S.
Takizawa, H. Somei, D. Jayaprakash, and H. Sasai, Angew.
Chem., Int. Ed., 42, 5711 (2003). e) R. Dorta, L. Shimon,
and D. Milstein, J. Organomet. Chem., 689, 751 (2004).
f) X. Wang and K. Ding, J. Am. Chem. Soc., 126, 10524
(2004). g) H. Guo, X. Wang, and K. Ding, Tetrahedron Lett.,
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K. Ding, J. Am. Chem. Soc., 127, 7694 (2005).
Furthermore, we examined the reuse of the insoluble organ-
ic–inorganic hybrid polymer. The recovery of the catalyst was
readily performed by centrifugation under air, and it was re-
vealed that the recovered catalyst could be recycled five times
without significant loss of catalyst activity (Table 3). The use
of molecular oxygen and a reusable catalyst, combine with a
broadly applicable method that exhibits low toxicity, establishes
this as clean, sustainable chemistry.
In summary, we have developed a Cu(II) ion containing
organic–inorganic hybrid polymer-catalyzed synthesis of ꢀ-
hydroxy ketones. Further studies on the application of the
organic–inorganic hybrid polymer to other reactions are under
progress.7
Published on the web (Advance View) October 27, 2005; DOI 10.1246/cl.2005.1590