First Metal- and Base-Free Selective Oxidative Coupling of Thiols in Neat Ionic Liquids
Table 3. Aerobic oxidation of thiols to disulfides catalysed Acknowledgements
[a]
by [hmim]Br.
RK, NS, UKS, AS are indebted to CSIR, New Delhi, for the
award of research fellowships. Authors gratefully acknowl-
edge the Director, IHBT Palampur, for providing necessary
laboratory facilities and funding under MLP0025. Thanks to
Mrs. Vijay Lata Pathania and Mr. Shiv Kumar for help re-
garding GC-MS and NMR analysis.
References
[
1] a) B. M. Trost, Acc. Chem. Res. 2002, 35, 695–705;
b) C.-J. Li, B. M. Trost, Proc. Natl. Acad. Sci. USA
2
008, 105, 13197–13202; c) G.-J. Brink, I. W. C. E.
Arends, R. A. Sheldon, Science 2000, 287, 1636–1639.
2] a) K. D. Lee, G. Saito, J. A. Swanson, Adv. Drug Deliv-
ery Rev. 2003, 55, 199–215; b) R. Bittman, Z. Li, P. Sa-
madder, G. Arthur, Cancer Lett. 2007, 251, 53–58;
c) J. P. Donahue, Chem. Rev. 2006, 106, 4747–4783;
d) Y. K. Ghosh, S. Balasubramanian, Angew. Chem.
[
2
2
003, 115, 2221–2223; Angew. Chem. Int. Ed. 2003, 42,
171–2173; e) T. Maddanimath, Y. B. Khollam, M.
[
[
a]
b]
Reaction conditions: 0.25 mmol thiol, ionic liquid
.25 mL, oxygen purged, temperature 508C.
Yield determined by GC-MS.
Aslam, I. S. Mulla, K. Vijayamohanan, J. Power Sources
2003, 124, 133–142.
[3] a) C. C. Silveira, S. R. Mendes, Tetrahedron Lett. 2007,
0
4
8, 7469–7471; b) J. Choi, N. M. Yoon, J. Org. Chem.
1
995, 60, 3266–3267; c) J. B. Arterburn, M. C. Perry,
S. L. Nelson, B. R. Dible, M. S. Holguin, J. Am. Chem.
Soc. 1997, 119, 9309–9310; d) N. Shefer, M. Carmeli, S.
Rozen, Tetrahedron Lett. 2007, 48, 8178–8181; e) A.
Hajipour, S. E. Mallakpour, H. Adibi, J. Org. Chem.
2
002, 67, 8666–8668; f) M. Carril, R. S. Martin, E.
Dominquez, I. Tellitu, Green Chem. 2007, 9, 315–317;
g) S. C. Banfield, A. T. Omori, H. Leish, T. Hudlcky, J.
Org. Chem. 2007, 72, 4989–4992; h) H. J. Kim, J. H.
Yoon, S. Yoon, J. Phys. Chem. A 2010, 114, 12010–
1
2015; i) A. Corma, T. Rodenas, M. J. Sabater, Chem.
Sci. 2012, 3, 398–404.
Figure 4. Recyclability of the ionic liquid.
[
4] a) A. Dhakshinamoorthy, M. Alvaro, H. Garcia, Chem.
Commun. 2010, 46, 6476–6478; b) H. Golchoubian, F.
Hosseinpoor, Catal. Commun. 2007, 8, 697–700;
c) J. L. G. Ruano, A. Parra, J. Aleman, Green Chem.
base-free, (iii) usage of molecular oxygen as a green
2
008, 10, 706–711; d) M. Oba, K. Tanaka, K. Nishiya-
oxidant, (iv) H O is the sole by-product (v) and high
2
ma, W. Ando, J. Org. Chem. 2011, 76, 4173–4177;
e) K. Y. D. Tan, G. F. Teng, W. Y. Fan, Organometallics
recyclability of IL besides easy isolation of products.
2
011, 30, 4136–4143; f) M. Montazerozohori, L. Z. Fra-
dombe, Phosphorus Sulfur Silicon Relat. Elem. 2010,
85, 509–515.
5] a) J. P. Hallett, T. Welton, Chem. Rev. 2011, 111, 3508–
1
[
Experimental Section
3576; b) P. Hapiot, C. Lagrost, Chem. Rev. 2008, 108,
2238–2264; c) R. D. Rogers, K. R. Seddon, Science
2003, 302, 792–793; d) P. Nockemann, K. Binnemans,
Typical Procedure
Thiophenol 1a (0.25 mmol), and ionic liquid [hmim]Br
K. Driesen, Chem. Phys. Lett. 2005, 415, 131–136; e) T.
Ogoshi, T. Onodera, T. Yamagishi, Y. Nakamoto, Mac-
romolecules 2008, 41, 8533–8536.
(
0.25 mL) were taken in a 25-mL round-bottom flask and
O was purged and the reaction mixture was stirred at 508C
2
for 30 min. After the completion of reaction, the reaction
mixture was cooled and taken up in diethyl ether (5ꢁ
[6] a) S. M. S. Chauhan, A. Kumar, K. A. Srinivas, Chem.
Commun. 2003, 2348–2349; b) A. R. Hajipour, M. Mos-
tafavi, A. E. Ruoho, Phosphorus Sulfur Silicon Relat.
Elem. 2009, 184, 1920–1923; c) D. Singh, F. Z. Galetto,
L. C. Soares, O. E. D. Rodrigues, A. L. Braga, Eur. J.
Org. Chem. 2010, 2661–2665; d) S. Thurow, V. A. Per-
10 mL). The combined organic layer was dried over anhy-
drous Na SO4 and vacuum evaporated using a rotavapor
2
(
Bꢂchi, Switzerland). The obtained product was analysed by
GC-MS which confirmed the formation of the disulfide.
Adv. Synth. Catal. 0000, 000, 0 – 0
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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