Esfahani, Chem. Commun., 2009, 5555; (p) S. Kanaoka, N. Yagi, Y.
Fukuyama, S. Aoshima, H. Tsunoyama, T. Tsukuda and H. Sakurai,
J. Am. Chem. Soc., 2007, 129, 12060; (q) K. Kaizuka, H. Miyamura
and S. Kobayashi, J. Am. Chem. Soc., 2010, 132, 15096; (r) K. Mori,
T. Hara, T. Mizugaki, K. Ebitani and K. Kaneda, J. Am. Chem. Soc.,
11 S. Wertz and A. Studer, Adv. Synth. Catal., 2011, 353,
69.
12 (a) B. Karimi, A. Biglari, J. H. Clark and V. Budarin, Angew. Chem., Int.
Ed., 2007, 46, 7210. For more recent leading references on immoblized-
TEMPO catalysts see; (b) J. Luo, C. Pardin, W. D. Lubell and X. X.
Zhu, Chem. Commun., 2007, 2136; (c) B. P. Mason, A. R. Bogdan,
A. Goswami and D. T. McQuad, Org. Lett., 2007, 9, 3449; (d) A.
Gheorghe, T. Chinnusamy, E. Cuevas-Ya n˜ ez, P. Hilgers and O. Reiser,
Org. Lett., 2008, 10, 4171; (e) A. P. Dobbs, M. J. Penny and P. Jones,
Tetrahedron Lett., 2008, 49, 6955; (f) M. A. Subhani, M. Beigi and P.
Eilbracht, Adv. Synth. Catal., 2008, 350, 2903; (g) A. Sch a¨ tz, R. N.
Grass, W. J. Stark and O. Reiser, Chem.–Eur. J., 2008, 14, 8262; (h) M.
Kuroboshi, K. Goto and H. Tanaka, Synthesis, 2009, 903; (i) J.-P. B.
Lindner, C. R o¨ ben, A. Studer, M. Stasiak, R. Ronge, A. Greiner and
H.-J. Wendorff, Angew. Chem., Int. Ed., 2009, 48, 8874; (j) C. R o¨ ben,
A. Studer, W. L. Hemme and H. Eckert, Synlett, 2010, 1110; (k) A. K.
Tucker-Schwartz and R. L. Garrell, Chem.–Eur. J., 2010, 16, 12718. For
recent interesting reviews on supported TEMPO catalysts see; (l) M.
Benaglia, A. Puglisi and F. Cozzi, Chem. Rev., 2003, 103, 3401; (m) F.
Cozzi, Adv. Synth. Catal., 2006, 348, 1367.
13 For typical examples of coating ionic liquids onto silica-supported
metal catalysts see: (a) Y. Gu, C. Ogawa, J. Kobayashi, C.
Mori and S. Kobayashi, Angew. Chem., Int. Ed., 2006, 45, 7217;
(b) Y. Gu, C. Ogawa and S. Kobayashi, Org. Lett., 2007, 9,
175.
14 See Electronic Supplementary Information† for details.
15 The optimum amounts of ionic liquid needed to fill mesopores of
SBA-15–TEMPO catalyst 1 was obtained based on the performance of
IL@SBA-15-TEMPO 2 containing different amounts of [BMIm]Br in
a typical aerobic oxidation of benzyl alcohol.
2
004, 126, 10657; (s) P. Maity, C. S. Gopinath, S. Bhaduri and G. K.
Lahiri, Green Chem., 2009, 11, 554; (t) Y. H. Ng, S. Ikeda, T. Harada, Y.
Morita and M. Matsumura, Chem. Commun., 2008, 3181; (u) B. Feng,
Z. Hou, H. Yang, X. Wang, Y. Hu, H. Li, Y. Qiao, X. Zhao and Q.
Huang, Langmuir, 2010, 26, 2505; (v) F. Rajabi and B. Karimi, J. Mol.
Catal. A: Chem., 2005, 232, 95.
For reviews of TEMPO-catalyzed alcohol oxidation, see: (a) A. E. J.
de Nooy, A. C. Besemer and H. van Bekkum, Synthesis, 1996, 1153;
6
(
2
b) W. Adam, C. R. Saha-Moller and P. A. Ganeshpur, Chem. Rev.,
001, 101, 3499; (c) R. A. Sheldon, I. W. C. E. Arends, G.-J. ten Brink
and A. Dijksman, Acc. Chem. Res., 2002, 35, 774; (d) R. A. Sheldon
and I. W. C. E. Arends, Adv. Synth. Catal., 2004, 346, 1051; (e) N.
Merbouth, J. M. Bobbitt and C. Br u¨ ckner, Org. Prep. Proced. Int.,
2
004, 36, 1; (f) T. Volger and A. Studer, Synthesis, 2008, 1979; (g) J.
M. Bobbitt, and C. Br u¨ ckner, Organic Reactions, John-Wiley & Sons,
New York, 2009.
7
For a recent review on aerobic oxidations in nitroxide-based oxidation
protocols see: J. Piera and J.-E. B a¨ ckvall, Angew. Chem., Int. Ed., 2008,
4
7, 3506. For a review on aerobic oxidation of alcohols using TEMPO
in the presence of metal co-catalysts see: R. A. Sheldon and I. W. C.
E. Arends, J. Mol. Catal. A: Chem., 2006, 251, 200.
8
9
R. Liu, X. Liang, C. Dong and X. Hu, J. Am. Chem. Soc., 2004, 126,
4
112.
(a) R. Liu, C. Dong, X. Liang and X. Hu, J. Org. Chem., 2005, 70, 729;
b) X. Wang, R. Liu, Y. Yin and X. Liang, Chem.–Eur. J., 2008, 14,
679; (c) Y. Xie, W. M. Mo, D. Xu, Z. L. Shen, N. Sun, B. Hu and X.
(
2
16 It has been shown that the coating of ionic liquid onto the silica
supported sulfonic acid led to a catalyst system with improved
selectivity in acid-catalyzed reactions: Y. Gu, A. Karam, F. J e´ r oˆ me
and J. Barrault, Org. Lett., 2007, 9, 3145.
17 In order to minimise the leaching of loaded ionioc liquid during the
recycling process it is crucial to use a non-polar solvent like n-heptane
in washing stages.
Hu, J. Org. Chem., 2007, 72, 4188; (d) X. He, Z. Shen, W. Mo, N. Sun,
B. Hu and X. Hu, Adv. Synth. Catal., 2009, 351, 89.
1
0 (a) C.-X. Miao, L.-N. He, J. L. Wang and F. Wu, J. Org. Chem., 2010,
5, 257. For the use of recyclable acidic imidazolium salts in TEMPO-
7
catalyzed aerobic oxidation of alcohols see: (b) C.-X. Miao, L.-N. He,
J.-Q Wang and J.-L. Wang, Adv. Synth. Catal., 2009, 351, 2209.
4
198 | Org. Biomol. Chem., 2011, 9, 4194–4198
This journal is © The Royal Society of Chemistry 2011