982
D.-M. Cui et al. / Tetrahedron Letters 51 (2010) 980–982
Soc. 1973, 95, 3414; (d) Stotter, P. L.; Hill, K. A. J. Org. Chem. 1973, 38, 2576; (e)
Table 3
Ionic liquid and catalyst recycling in hydrative cyclization of 1aa
Kuehne, M. E.; Parsons, W. H. J. Org. Chem. 1977, 42, 3408; (f) Dauben, W. G.;
Michno, D. M. J. Org. Chem. 1977, 42, 682; (g) Chong, B.-D.; Ji, Y.-I.; Oh, S.-S.;
Yang, J.-D.; Baik, W.; Koo, S. J. Org. Chem. 1997, 62, 9323; (h) Hareau, G. P.-J.;
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Corey, E. J. Org. Lett. 2000, 2, 1097.
Entry
1
2
3
4
5
6
Yieldb (%)
78
74
76
76
72
75
a
3. Zhang, C.; Cui, D.-M.; Yao, L.-Y.; Wang, B.-S.; Hu, Y.-Z.; Hayashi, T. J. Org. Chem.
2008, 73, 7811.
The reactions were performed with 1a (0.5 mmol), H2O (0.5 mmol), MeSO3H
(50 mol %), and (PPh3)AuNO3 (5 mol %) in [bmim]BF4 (1 mL) and MeOH (1 mL) at
4. For recent reviews, see: (a) Chiappe, C.; Pieraccini, D. J. Phys.Org. Chem. 2005, 18,
275; (b) Jain, N.; Kumar, A.; Chauhan, S.; Chauhan, S. M. S. Tetrahedron 2005, 61,
1015; (c) Murugesan, S.; Linhardt, R. J. Curr. Org. Synth. 2005, 2, 437; (d)
Chowdhury, S.; Mohan, R. S.; Scott, J. L. Tetrahedron 2007, 63, 2363; (e) Imperato,
G.; König, B.; Chiappe, C. Eur. J. Org. Chem. 2007, 7, 1049; (f) El Seoud, O. A.;
Koschella, A.; Fidale, L. C.; Dorn, S.; Heinze, T. Biomacromolecules 2007, 8, 2629;
(g) Parvulescu, V. I.; Hardacre, C. Chem. Rev. 2007, 107, 2615; (h) van Rantwijk,
F.; Sheldon, R. A. Chem. Rev. 2007, 107, 2757; (i) Weingärtner, H. Angew. Chem.,
Int. Ed. 2008, 47, 654.
5. (a) Ellis, B.; Keim, W.; Wasserscheid, P. Chem. Commun. 1999, 337; (b) Mathews,
C. J.; Smith, P. J.; Welton, T. Chem. Commun. 2000, 1249; (c) Owens, G. S.; Abu-
Omar, M. M. Chem. Commun. 2000, 1165; (d) Wasserscheid, P.; Waffenschmidt,
H.; Machnitzti, P.; Kottsieper, K. W.; Stelzer, O. Chem. Commun. 2001, 451; (e)
Namboodiri, V. V.; Varma, R. S.; Sahle-Demessie, E.; Pillai, U. R. Green Chem.
2002, 4, 170; (f) Park, S. B.; Alper, H. Org. Lett. 2003, 5, 3209; (g) Webb, P. B.;
Sellin, M. F.; Kunene, T. E.; Williamson, S.; Slawin, A. M. Z.; Cole-Hamilton, D. J. J.
Am. Chem. Soc. 2003, 125, 15577; (h) Brausch, N.; Metlen, A.; Wasserscheid, P.
Chem. Commun. 2004, 1552; (i) Wolfson, A.; Vankelecom, I. F. J.; Jacobs, P. A. J.
Organomet. Chem. 2005, 690, 3558; (j) Cassol, C. C.; Umpierre, A. P.; Machado, G.;
Wolke, S. I.; Dupont, J. J. Am. Chem. Soc. 2005, 127, 3298; (k) Mo, J.; Xu, L.; Xiao, J.
J. Am. Chem. Soc. 2005, 127, 751; (l) Li, S.; Lin, Y.; Xie, H.; Zhang, S.; Xu, J. Org. Lett.
2006, 8, 391; (m) Wang, R.; Twamley, B.; Shreeve, J. M. J. Org. Chem. 2006, 71,
426.
70 °C for 3 h.
b
Isolated yields.
Moreover, we attempted a recycling of the ILs-catalyst system.
After 3 h at 70 °C, the mixture was extracted with diethyl ether,
dried under vacuum, and added to the same amount of diynes,
H2O, MeSO3H, and MeOH. We showed that ILs containing the gold
catalyst can be reused five times without any loss of activity.
Examples of the reaction carried out in the recycled [bmim]BF4
are presented in Table 3. The yields of cyclohexenone were basi-
cally similar to those observed using fresh non-recycled ionic
liquid.
We have shown that hydrative cyclization of 1,6-diynes pro-
ceeds in ionic liquid media which acts as an excellent co-solvent.8
The gold catalyst in the ionic liquid could be recycled in five sub-
sequent reactions without the loss of the reaction efficiency. The
good yields were observed for a variety of terminal diynes.
6. (a) Antoniotti, S.; Genin, E.; Michelet, V.; Genêt, J.-P. J. Am. Chem. Soc. 2005, 127,
9976; (b) Oh, C. H.; Yi, H. J.; Lee, J. H. New J. Chem. 2007, 31, 835.
7. Sperger, C.; Fiksdahl, A. Org. Lett. 2009, 11, 2449.
Acknowledgment
8. General procedure for the hydrative cyclization of diynes in ionic liquids: To a
reactor containing diyne (0.5 mmol), methanol (1 mL), ionic liquids (1 mL), and
H2O (0.5 mmol) were added (Ph3P)Au NO3 (5 mol %) and CH3SO3H (50 mol %)
under nitrogen. The resulting yellow solution was then sealed and stirred at
70 °C until the starting diyne was consumed as judged by TLC. Methanol was
removed and diethyl ether (5 Â 2 mL) was added to the contents and stirred.
The supernatant diethyl ether layer containing the product was decanted. The
diethyl ether layer was washed with brine, dried over Na2SO4, and concentrated
in vacuo. The residue was purified by column chromatography (silica gel) to
yield cyclized product in an analytically pure form. The recovered ionic liquid
containing the gold catalyst was concentrated in vacuo and was reused in the
next run.
This work was partially supported by the Natural Science Foun-
dation of China (Nos. 20672099, 20572094).
References and notes
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