Y. Song et al. / Tetrahedron Letters 43 (2002) 6625–6627
1041.
6627
however, when water was used as both solvent and
resolution reagent, very good activity and enantioselec-
tivity were demonstrated (entry 20). It is worthwhile to
note that the ee’s of diols obtained by using the recov-
ered catalyst 1 are better than those using the fresh
catalyst 1 (entries 20 and 21). We suppose that the
recovered catalyst 1 may be modified by the presence of
hydrophilic groups at both ends of the polymer chain
during the HKR of epichlorohydrin. Because an exces-
sive amount of (R,R)-1,2-diaminocyclohexane is used
for the synthesis of the polymeric ligand, two free -NH2
might exist at both ends of the polymer ligand. When
epichlorohydrin is employed as substrate, part of the
epoxide reacts not only with H2O, but also with these
terminal -NH2 groups, thus resulting in the water-solu-
ble catalyst.
5. Rodriguez, A.; Nomen, M.; Spur, B. W.; Godfroid, J. J.;
Lee, T. H. Tetrahedron 2001, 57, 25–37.
6. Gu, J.; Dirr, M. J.; Wang, Y.; Scoper, D. L.; De, B.;
Wos, J. A.; Johnson, C. R. Org. Lett. 2001, 3, 791–794.
7. Schaus, S. E.; Brandes, B. D.; Larrow, J. F.; Tokunaga,
M.; Hansen, K. B.; Gould, A. E.; Furrow, M. E.; Jacob-
sen, E. N. J. Am. Chem. Soc. 2002, 124, 1307–1315.
8. Jacobsen, E. N.; Wu, M. H. In Comprehensive Asymmet-
ric Catalysis; Jacobsen, E. N.; Pfaltz, A.; Yamamoto, H.,
Eds.; Springer: New York, 1999; pp. 1309–1326.
9. Jacobsen, E. N. Acc. Chem. Res. 2000, 33, 421–431.
10. Konsler, R. G.; Karl, J.; Jacobsen, E. N. J. Am. Chem.
Soc. 1998, 120, 10780–10781.
11. Kureshy, R. I.; Khan, N. H.; Abdi, S. H. R.; Patel, S. T.;
Jasra, R. V. J. Mol. Chem. A: Chem. 2002, 179, 1–2 and
73–77.
In summary, the kinetic resolution of terminal epoxides
proceeds smoothly with poly-salen-Co(III) complexes
to give excellent chemical yields and high ee’s. It was
found that the terminal groups of these polymeric
catalysts can be modified to hydrophilic groups during
the HKR of epichlorohydrin and the modified catalysts
may promote the reaction with better enantioselectivi-
ties and provide a much easier isolation procedure.
12. Joseph, M. R.; Jacobsen, E. N. J. Am. Chem. Soc. 2001,
123, 2687–2688.
13. Joseph, M. R.; Jacobsen, E. N. Angew. Chem., Int. Ed.
2002, 41, 1374–1377.
14. Annis, D. A.; Jacobsen, E. N. J. Am. Chem. Soc. 1999,
121, 4147–4154.
15. Osburn, P. L.; Bergbreiter, D. E. Prog. Polym. Sci. 2001,
26, 2015–2081.
16. Breinbauer, R.; Jacobsen, E. N. Angew. Chem., Int. Ed.
2000, 39, 3604–3607.
17. Kim, G.-J.; Park, D.-W. Catal. Today 2000, 63, 537–547.
18. Yao, X.; Chen, H.; Lu¨, W.; Pan, G.; Hu, X.; Zheng, Z.
Tetrahedron Lett. 2000, 41, 10267.
19. Song, Y.; Yao, X.; Chen, H.; Pan, G.; Hu, X.; Zheng, Z.
J. Chem. Soc., Perkin. Trans. 1 2002, 870–873.
20. Tokunaga, M.; Larrow, J. F.; Kakiuchi, F.; Jacobsen, E.
N. Science 1997, 277, 936–938 (activation of the recov-
Acknowledgements
This work was supported by the National Natural
Science Foundation of China (29933050).
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