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Fig. 2. α-Tfm-Alanine containing dipeptides.investigated. Because of the strong deactivation of the amino group and the steric bulkinessof the CF 3 group, specific activation methods (mixed anhydrides [11] or amino acidbromides [12-14]) were already reported in the literature for N-terminal couplings ofα-Tfm-AAs. In order to elaborate a tripeptide building block suitably protected for peptidesynthesis, we decided to perform the coupling reaction with an Fmoc-protected amino acidchloride. The corresponding tripeptide was obtained in 74% yield without anyepimerization (Figure 3).Fig. 3. α-Tfm-Alanine containing tripeptide.AcknowledgmentsWe thank Central Glass Company for financial support. We also thank the French Fluorine Network.References1. Ojima, I. Fluorine in Medicinal Chemistry and Chemical Biology Wiley, 2009.2. Koksch, B., Sewald, N., Hofmann, H.-J., Burger, K., Jakubke, H.-D. J. Pept. Sci. 3, 157-167 (1997).3. Jäckel, C., Koksch, B. Eur. J. Org. Chem. 4483-4503 (2005).4. Maisch, D., Wadhwani, P., Afonin, S., Bottcher, C., Koksch, B., Ulrich, A.S. J. Am. Chem. Soc.131, 15596-15597 (2009).5. Huguenot, F., Brigaud, T. J. Org. Chem. 71, 7075-7078 (2006).6. Huguenot, F., Brigaud, T. J. Org. Chem. 71, 2159-2162 (2006).7. Chaume, G., Van Severen, M.C., Marinkovic, S., Brigaud, T. Org. Lett. 8, 6123-6126 (2006).8. Chaume, G., Van Severen, M.C., Ricard, L., Brigaud, T. J. Fluorine Chem. 129, 1104-1109 (2008).9. Caupène, C., Chaume, G., Ricard, L., Brigaud, T. Org. Lett. 11, 209-212 (2009).10. Chaume, G., Lensen, N., Caupène, C., Brigaud, T. Eur. J. Org. Chem. 5717-5724 (2009).11. Koksch, B., Quaedflieg, P.J.L.M., Michel, T., Burger, K., Broxterman, Q.B., Schoemaker, H.E.Tetrahedron: Asymmetry 15, 1401-1407 (2004).12. Dal Pozzo, A., Bergonzi, R., Ni, M. Tetrahedron Lett. 42, 3925-3927 (2001).13. Dal Pozzo, A., Ni, M., Muzi, L., de Castiglione, R., Mondelli, R., Mazzini, S., Penco, S., Pisano,C., Castorina, M., Giannini, G. J. Med. Chem. 49, 1808-1817 (2006).14. Dal Pozzo, A., Ni, M., Muzi, L., Caporale, A., de Casteglione, R., Kaptein, B., Broxterman, Q.B.,Fromaggio, F. J. Org. Chem. 67, 6372-6375 (2002).73