X. Ding et al. / Tetrahedron Letters 47 (2006) 2921–2924
2923
a
Table 3. CM of different substrates catalyzed by 2 in [BMIM]PF
6
achieved. Most important, the process was friendly to
the environment according to the conception of ‘green’
chemistry. The study of the second-generation Hov-
eyda–Grubbs catalyst 5 with broad functional groups
tolerance and ease of use for highly electron deficient
olefins of CM is currently underway in our laboratory
and these results will be reported in due course.
b
Entry
Substrate
Conditions
Product
Cycle Yield (%)
1
2
3
4
89
84
80
75
1
2 mol% of 2
RT 4 h
1
1
3
5
14
Cl
1
2
3
4
81
79
75
63
Acknowledgements
2
3 mol% of 2
o
Cl
50 C 4 h
This work was supported by elitist funds from the gov-
ernor of Guizhou province.
16
Cl
1
2
15
64
CN
18
c
c
References and notes
3
4
5 mol% of 2
CN
o
50 C 12 h
CN
1
. For recent reviews on olefin metathesis, see: (a) F u¨ rstner,
A. Angew. Chem., Int. Ed. 2002, 39, 3012; (b) Trnka, T.
M.; Grubbs, R. H. Acc. Chem. Res. 2001, 34, 18; (c)
Schrock, R. R.; Hoveyda, A. H. Angew. Chem., Int. Ed.
1
7
1
2
0
75
5
mol% of 2
o
5
0 C 12 h
2
003, 42, 4592; (d) Grubbs, R. H. Tetrahedron 2004, 54,
7
117.
1
9
20
2. (a) Schwab, P.; France, M. B.; Ziller, J. W.; Grubbs, R. H.
Angew. Chem., Int. Ed. Engl. 1995, 34, 2039; (b) Schwab,
P.; Grubbs, R. H.; Ziller, J. W. J. Am. Chem. Soc. 1996,
118, 100.
1
2
0
0
NH
c
3
. Scholl, M.; Ding, S.; Lee, C. W.; Grubbs, R. H. Org. Lett.
1999, 1, 953.
5
5
mol% of 2
NH
o
5
0 C 12 h
4. (a) Scholl, M.; Trnka, T. M.; Morgan, J. P.; Grubbs, R. H.
Tetrahedron Lett. 1999, 40, 2247; (b) Huang, J.; Stevens,
E. D.; Nolan, S. P.; Petersen, J. L. J. Am. Chem. Soc. 1999,
HN
22
2
1
1
21, 2674.
5
6
. Cho, J. H.; Kim, B. M. Org. Lett. 2003, 5, 531.
. Kingsbury, J. S.; Harrity, J. P. A.; Bonitatebus, P. J.;
Hoveyda, A. H. J. Am. Chem. Soc. 1999, 121, 791.
O
6
1
2
0
0
5
mol% of 2
7. Garber, S. B.; Kingsbury, J. S.; Gray, B. L.; Hoveyda, A.
O
o
c
5
0 C 12 h
O
H. J. Am. Chem. Soc. 2000, 122, 8168.
8
. For recent reviews on ionic liquids and their application in
transition metal-catalyzed reactions, see: (a) Welton, T.
Chem. Rev. 1999, 99, 2071; (b) Wasserscheid, P.; Keim, W.
Angew. Chem., Int. Ed. 2000, 39, 3772; (c) Sheldon, R.
Chem. Commun. 2001, 2399; (d) Dupont, J.; De Souza, R.
F.; Suarez, P. A. Chem. Rev. 2002, 102, 3667; (e)
Wasserscheid, P.; Welton, T. Ionic liquids in synthesis;
Wiley-VCH: Weinheim, Germany, 2003; (f) Doherty, S.;
Goodrich, P.; Hardacre, C.; Luo, H.-K.; Rooney, D. W.;
Seddon, K. R.; Styring, P. Green Chem. 2004, 6, 63.
. Yao, Q.; Zhang, Y. Angew. Chem., Int. Ed. 2003, 42,
2
3
24
a
2
All reactions were performed under N .
b
Isolated yield after extraction with petroleum ether followed by
purification by silica gel column chromatography and only E-isomers
were obtained in all cases.
c
Reactions were performed with 13.
9
3
395.
0. Yao, Q.; Sheets, M. J. Organomet. Chem. 2005, 690,
577.
11. Clavier, H.; Audic, N.; Guillemin, J.-C. Chem. Commun.
2004, 2282.
1
3
Mes
Mes
Ph
Mes
Mes
Ph
Cl
Cl
- PCy
3
Cl
Cl
Ru
Ru
PCy
3
1
1
1
2. Clavier, H.; Audic, N.; Guillemin, J.-C.; Mauduit, M. J.
1
4 e
Organomet. Chem. 2005, 690, 3585.
3. Mayo, K. G.; Nearhoof, E. H.; Kiddle, J. J. Org. Lett.
2002, 4, 1567.
4. Csihony, S.; Fischmeister, C.; Bruneau, C.; Horvath, I. T.;
Dixneuf, P. H. New J. Chem. 2002, 26, 1667.
2
24
Scheme 1.
.21 When loading the most active substrate 13 to the
recovered ionic liquid, no desired product appeared.
15. Some descriptions about catalyst leaching were also
reported in Refs. 9, 10 and 12. Evaporation of dimethyl
ether from the organic phase gave a crude reaction
mixture and TLC showed styrene had completely con-
verted. The crude reaction mixture was then dissolved in
2
In summary, we have reported that ionic liquids acted as
powerful media for CM showing great advantages over
traditional organic solvent. Convenient catalysts recy-
cling, as well as acceleration of reaction rate were
2 2
CH Cl and recharged another portion of p-methylstyrene
13. After heating the mixture to 45 ꢁC for 4 h, the product
14 could be observed. The experiment was the direct