Synthesis of N-heterocycles via lactam-derived ketene aminal phosphates. Asymmetric synthesis of cyclic amino acids.

Abstract

A variety of N-heterocycles can be synthesized from lactams via Pd⁰-catalyzed couplings of their corresponding enol phosphates.

References

1. For the use of lactam-derived enol triflates in carbon–carbon bond forming reactions, see: T. Okita and M. Isobe, Synlett, 1994, 589; T. Okita and M. Isobe, Tetrahedron, 1995, 51, 3737; T. Luker, H. Hiemstra and W. N. Speckamp, Tetrahedron Lett., 1996, 37, 8257; T. Luker, H. Hiemstra and W. N. Speckamp, J. Org. Chem., 1997, 62, 3592; T. Luker, H. Hiemstra and W. N. Speckamp, J. Org. Chem., 1997, 62, 8131.
2. For the use of lactone-derived ketene acetal phosphates, see: K. C. Nicolaou, G.-Q. Shi, J. L. Gunzner, P. Gärtner and Z. Yang, J. Am. Chem. Soc., 1997, 119, 5467.
3. The larger lactams were synthesized from the corresponding ketones via a Beckmann rearrangement, see: G. A. Olah and A. P. Fung, Synthesis, 1979, 537.
4. W. J. Scott and J. K. Stille, J. Am. Chem. Soc., 1986, 108, 3033.
5. BINAP has been previously used as a superior ligand to monodentate and other bidentate systems in aromatic amination; see: J. P. Wolfe, S. Wagaw and S. L. Buchwald, J. Am. Chem. Soc., 1996, 118, 7215.
6. For a catalytic hydrogenation review, see: R. Noyori, Asymmetric Catalysis In Organic Synthesis, Wiley-Interscience, New York, 1994, ch. 2.
7. To the best of our knowledge, there is only one example of a catalytic asymmetric hydrogenation of a cyclic dehydroamino acid derivative, see: C. J. Foti and D. L. Comins, J. Org. Chem., 1995, 60, 2656.
8. M. J. Burk, M. F. Gross, T. Gregory, P. Harper, C. S. Kalberg, J. R. Lee and J. P. Martinez, Pure Appl. Chem., 1996, 68, 37.