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Fig. 3. Synthesis of (S)- and (R)-α-Tfm–Aspartic Acid in enantiopure form.described procedure [13], the expected CF 3 -oxazolidines were obtained in a 80/20diastereomeric ratio in mixture with the enamine derivative (Figure 2). The crude mixturewas then engaged in the Strecker-type reaction to afford the corresponding amino nitriles.At this stage, an acidic treatment of the amino nitriles in ethyl acetate allowed thehydrolysis of the cyano group and the formation of the corresponding morpholinones(Figure 3). A concentrated HCl treatment of the separated (S,R) and (R,R) diastereomersprovided the clean removal of the chiral auxiliary and the hydrolysis of the ester group togive respectively the (S)- and the (R)-α-Tfm aspartic acid in enantiopure form and in goodoverall yield. The absolute configuration was again determined by correlation with theoptical rotation reported in the literature [14,15].AcknowledgmentsWe thank Central Glass Company for financial support. We also thank the French Fluorine Network.References1. Smiths, R., Cadimaco, C.D., Burger, K., Koksch, B. Chem. Soc. Rev. 37, 1727-1739 (2008).2. Kukhar, V.P., Soloshonok, V.A. Fluorine Containing Amino Acids: Synthesis and Properties.Wiley, New York, 1995.3. Brigaud, T., Chaume, G., Pytkowicz, J., Huguenot, F. Chim. Oggi. 25, 8-10 (2007).4. Lebouvier, N., Laroche, C., Huguenot, F., Brigaud, T. Tetrahedron Lett. 43, 2827-2830 (2002).5. Huguenot, F., Brigaud, T. J. Org. Chem. 71, 2159-2162 (2006).6. Huguenot, F., Brigaud, T. J. Org. Chem. 71, 7075-7078 (2006).7. Caupène, C., Chaume, G., Ricard, L., Brigaud, T. Org. Lett. 11, 209-212 (2009).8. Chaume, G., Van Severen, M.C., Ricard, L., Brigaud, T. J. Fluorine Chem. 129, 1104-1109 (2008).9. Chaume, G., Van Severen, M.C., Marinkovic, S., Brigaud, T. Org. Lett. 8, 6123-6126 (2006).10. Chaume, G., Lensen, N., Caupène, C., Brigaud, T. Eur. J. Org. Chem. 5717-5724 (2009).11. Pytkowicz, J., Stéphany, O., Marinkovic, S., Inagaki, S., Brigaud, T. Org. Biomol. Chem. ASAPDOI: 10.1039/C0OB00424C (2010).12. Bravo, P. Viani, F., Zanda, M., Soloshonok, V.A. Gazz. Chim. Ital. 125, 149-150 (1995).13. Ishida, Y., Iwahashi, N., Nishizono, N., Saigo, K. Tetrahedron Lett. 50, 1889-1892 (2009).14. Lazzaro, F., Gissot, A., Crucianelli, M., De Angelis, F., Bruché, L., Zanda, M. Lett. Org. Chem. 2,235-237 (2005).15. Lazzaro, F., Crucianelli, M., De Angelis, F., Frigerio, M., Malpezzi, L., Volonterio, A., Zanda, M.Tetrahedron: Asymmetry 15, 889-893 (2004).75