2424
G. Haberhauer / Tetrahedron Letters 49 (2008) 2421–2424
E.; MacGloinn, C. Chem. Commun. 2003, 1274; (c) Nagasato, S.;
In the case of the tridentate ligand 1c, too, the reaction
Sunatsuki, Y.; Ohsato, S.; Kido, T.; Matsumoto, N.; Kojima, M.
Chem. Commun. 2002, 14; (d) Matsumoto, K.; Ozawa, T.; Jitsukawa,
K.; Einaga, H.; Masuda, H. Chem. Commun. 2001, 978; (e) Uppadine,
L. H.; Drew, M. G. B.; Beer, P. D. Chem. Commun. 2001, 291; (f)
Weizman, H.; Libman, J.; Shanzer, A. J. Am. Chem. Soc. 1998, 120,
2188; (g) Tor, Y.; Libman, J.; Shanzer, A.; Felder, C. E.; Lifson, S. J.
Am. Chem. Soc. 1992, 114, 6661.
with metal salts leads to a diastereoselective complex
formation (Fig. 3 and Table 1). The three pyridine arms
are arranged propeller-like around the metal center. Such
a helically controlled propeller-like arrangement in labile
coordination complexes has been observed in only a few
systems up to date.14 According to B3LYP/6-31G* calcula-
tions, the energy difference between the K-isomer of
4. See, for example: (a) Fabris, F.; Pellizzaro, L.; Zonta, C.; De Lucchi,
O. Eur. J. Org. Chem. 2007, 283; (b) Heinrichs, G.; Kubik, S.; Lacour,
J.; Vial, L. J. Org. Chem. 2005, 70, 4498; (c) Postnikova, B. J.; Anslyn,
E. V. Tetrahedron Lett. 2004, 45, 501; (d) Schopohl, M. C.; Siering,
C.; Kataeva, O.; Waldvogel, S. R. Angew. Chem., Int. Ed. 2003, 42,
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Kim, S.-G.; Kim, K.-H.; Jung, J.; Shin, S. K.; Ahn, K. H. J. Am.
Chem. Soc. 2002, 124, 591; (g) Hennrich, G.; Anslyn, E. V. Chem. Eur.
J. 2002, 8, 2218; (h) Cousins, G. R. L.; Furlan, R. L. E.; Ng, Y.-F.;
Redman, J. E.; Sanders, J. K. M. Angew. Chem., Int. Ed. 2001, 40,
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1cÁZn2+ and the D-isomer amounts to 33.3 kJ molÀ1
.
In summary, we could show that three arms can be fixed
on an imidazole-containing hexapeptide, the conformation
of which is controlled via three peptide-like b-turns. The
helicity of the arms thus can be predicted, which allows
the diastereoselective synthesis of various—even kinetically
labile—octahedral metal complexes. This concept of using
peptide-like b-turns for the structure formation in C3-sym-
metric systems should be applicable to other systems, too.
5. See, for example: (a) Hennrich, G.; Omenat, A.; Asselberghs, I.;
Foerier, S.; Clays, K.; Verbiest, T.; Serrano, J. L. Angew. Chem., Int.
Acknowledgments
ˇ
´
Ed. 2006, 45, 4203; (b) Wu, J.; Tomovic, Z.; Enkelmann, V.; Mullen,
¨
K. J. Org. Chem. 2004, 69, 5179; (c) Albrecht, M. Angew. Chem., Int.
Ed. 1999, 38, 3463.
The authors thank the DFG for financial support. We
are grateful to Dr. Andreea Schuster for many helpful
discussions.
6. See, for example: (a) Katagiri, H.; Tanaka, Y.; Furusho, Y.; Yashima,
E. Angew. Chem., Int. Ed. 2007, 46, 2435; (b) Haberhauer, G.; Oeser,
T.; Rominger, F. Chem. Commun. 2005, 2799; (c) Albrecht, M.;
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2086; (e) Albrecht, M. Chem. Rev. 2001, 101, 3457; (f) von Zelewsky,
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Supplementary data
Supplementary data associated with this article can be
7. (a) Haberhauer, G.; Oeser, T.; Rominger, F. Chem. Eur. J. 2005,
6718; (b) Haberhauer, G.; Oeser, T.; Rominger, F. Chem. Commun.
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References and notes
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