D. S. Gaikwad et al. / Tetrahedron Letters 53 (2012) 3077–3081
3081
I
2 mol% Pd(OAc)2
O
R
R
+
O
Et3N, IL
100 °C, 4-5h
6
7
Hydrolysis
O
R= OMe, Me
R
9
Scheme 3. Heck arylation of ethylvinylether with aryl halides.
D. Appl. Catal. A 2010, 373, 1; (f) Dupont, J.; Scholten, J. D. Chem. Soc. Rev. 2010,
39, 1780.
100
90
80
70
60
50
40
30
20
10
0
5. (a) Mathews, C. J.; Smith, P. J.; Welton, T. Chem. Commun. 2000, 1249; (b)
Fernandez, F.; Cordero, B.; Durand, J.; Muller, G.; Malboosc, F.; Kihn, Y.; Teuma,
E.; Gomez, M. Dalton Trans. 2007, 5572; (c) Handy, S. T. Synlett 2006, 3176.
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Suarewz, P. A. Z. Chem. Rev. 2002, 102, 3667; (c)Ionic Liquids in Synthesis;
Wassercheid, P., Welton, T., Eds.; Wiley-VCH: Weinheim, Germany, 2003.
7. (a) Calo, V.; Nacci, A.; Monopoli, A.; Fornaro, A.; Sabbatini, L.; Cioffi, N.;
Ditaranto, N. Organometallics 2004, 23, 5154; (b) Calo, V.; Nacci, A.; Monopoli,
A.; Ieva, E.; Cioffi, N. C. Org. Lett. 2005, 7, 617.
8. (a) Li, G. Y. Angew. Chem. 2001, 113, 1561; (b) Morita, D. K.; Stille, J. K.; Norton, J.
R. J. Am. Chem. Soc. 1995, 117, 8576; (c) Martin, R.; Buchwald, S. L. Acc. Chem.
Res. 2008, 41, 1461.
9. (a) Jeffery, T. Tetrahedron Lett. 1985, 26, 2667; (b) Amatorc, C.; Azzabi, M.;
Jutand, A. J. Am. Chem. Soc. 1991, 113, 8375; (c) Prockl, S. S.; Kleist, W.; Kohler,
K. Catal. Lett. 2008, 125, 197.
1
2
3
No. of recycle
4
5
10. (a) Cassol, C. C.; Umpierre, A. P.; Machado, G.; Wolke, S. I.; Dupont, J. J. Am.
Chem. Soc. 2005, 127, 3298; (b) Karl, S. A.; Vallin, P. E.; Mats, L.; Hallberg, A. J.
Org. Chem. 2002, 67, 6243.
11. (a) Pore, D. M.; Desai, U. V.; Thopate, T. S.; Wadgaonkar, P. P. Aust. J. Chem. 2007,
60, 435; (b) Pore, D. M.; Shaikh, T. S.; Undale, K. A.; Gaikwad, D. S. C. R. Chimie
2010, 13, 1429; (c) Undale, K. A.; Park, Y. K.; Park, K. M.; Dagade, D. H.; Pore, D.
M. Synlett 2011, 791.
12. Carmichael, A. J.; Earle, M. J.; Holbrey, J. D.; MaCormac, P. B.; Seddon, K. R. Org.
Lett. 1999, 1, 997.
13. Cai, Y. Q.; Lu, Y.; Liu, Y.; Hua, G. G. Catal. Lett. 2007, 119, 154.
14. Typical procedure: Aryl halide (1 mmol), olefin (1.1 mmol), Et3N (2 mmol),
Pd(OAc)2 (2 mol %), and IL 5 (2 mL) were added in a 25 mL round bottomed
flask. The mixture was stirred vigorously at 100 °C for the time mentioned in
Table 3. After cooling to room temperature, the desired product was isolated
from IL by extracting with 3% ethyl acetate in petroleum ether (7 mL Â 5). The
product obtained after evaporation of the solvent was purified by column
chromatography (silica mesh size 60–120).
Figure 4. Recycle study of the Pd-NPs/IL 5 for the Heck reaction.
In summary, we have developed an ecofriendly cost-effective
method for Heck reaction catalyzed by in situ formed Pd-nanopar-
ticles in hydrophobic IL under ligand-free conditions. The reaction
of olefins with iodoarenes, bromoarenes, and chloroarenes gener-
ated the corresponding coupling product in good to excellent yields.
Acknowledgments
One of the authors D.S.G. thanks the UGC-SAP BSR New Delhi
for the research fellowship and Y.P. appreciates financial support
by the Ministry of Knowledge Economy, Korea through the Cleaner
Production Technology Development Project.
15. Heck arylation of ethyl vinyl ether: 4-Methoxy/methyl iodobenzene (1 mmol),
ethyl vinyl ether (5 mmol), Et3N (2 mmol), Pd(OAc)2 (2 mol %) and IL 5 (2 mL)
were added in a 25 mL round bottomed flask. The mixture was stirred vigorously
at 100 °C for 4 h. After cooling to room temperature, aqueous HCl (5%, 5 mL) was
added and the mixture was stirred for 0.5 h, the desired product was isolated by
extractingwith ethyl acetate andwater. The product obtained after evaporationof
the solvent was purified by column chromatography (silica mesh size 60–120).
16. Preparation of ionic liquid (1-octyl-3-methylimidazolium nonafluorobutane
sulfonate): To a vigorously stirred solution of 1-methylimidazole (50 mmol)
in toluene (25 mL), 1-bromo octane (55 mmol) was slowly added at 0 °C. The
quaternisation reaction was carried out at 80 °C for 24 h, after which it was
placed in a freezer at 0 °C for 4 h. Toluene was decanted and the remaining
viscous oil was repeatedly washed with ethyl acetate to yield yellow oil, which
was dried in vacuum to give [OMIM]Br in approximately 90% yield. [OMIM]Br
was dissolved in acetone and followed by addition of potassium
1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulfonate and stirred it for 48 h at room
temperature. The suspension was filtered to remove the precipitated bromide
salt and the solvent was evaporated under reduced pressure. Again it was
dissolved in dichloromethane washed repeatedly with small volumes of water
(30 mL) until no precipitation of AgBr occurred in the aqueous phase on
addition of a AgNO3 solution. The organic phase was then washed two times
with water to ensure complete removal of the bromide salt. The solvent was
removed in vacuum until no visible signs of solvents and water, resulting into
corresponding ionic liquid in 92%.
Supplementary data
Supplementary data associated with this article can be found, in
References and notes
1. (a)The Mizoroki–Heck reaction; Oestreich, M., Ed.; John Wiley & Sons Ltd: New
York, 2009; (b) Beletskaya, I. P.; Cheprakov, A. V. In Handbook of
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York, NY, 2002; Vol. 2, p 2957; (c) Beletskaya, I. P.; Cheprakov, A. V. Chem. Rev.
2000, 100, 3009.
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17. Spectral data for IL (5): 1H NMR (DMSO-d6, 300 MHz): d 0.81 (s, 3H), 1.22 (s,
10H), 1.75 (s, 2H), 3.82 (s, 3H), 4.12 (t, 2H), 7.66–7.72 (d, 2H), 9.05 (s, 1H); 13
C
NMR (DMSO-d6, 75 MHz): 13.22, 22.08, 25.75, 28.59, 28.67, 29.72, 31.34, 35.78,
49.28, 122.64, 123.97, 136.89 [due to presence of 9F atoms in anion the 13C
NMR became complicated and appears signals in 104.98–119.86]; 19FNMR
(400 MHz, DMSO-d6): d À81.04 (s, CF3), À115.13 (s, CF2), À121.69 (s, CF2),
À126.14 (s, CF2); MS (ESI): m/z 195.2 (+ve mode), 298.9 (Àve mode).