Iron(III) 2-ethylhexanoate as a novel, stereoselective hetero-Diels–Alder catalyst

Abstract

Iron(III) 2-ethylhexanoate has been used as a novel, mild Lewis acid catalyst for the stereoselective Diels–Alder reaction of ethyl (E)-4-oxobutenoate with alkyl vinyl ethers to stereoselectively produce cis-2-alkoxy-3,4-dihydro-2H-pyran-4-carboxylic acid, ethyl esters with diastereoisomeric excesses (de) as high as 98%.

References

1. For selected reviews of the Diels–Alder reaction, see U. Pindur, G. Lutz and C. Otto, Chem. Rev., 1993, 93, 741; H. B. Kagan and O. Riant, Chem. Rev., 1992, 92, 1007; G. Desimoni and G. Tacconi, Chem. Rev., 1975, 75, 651; A. Wasserman, Diels–Alder Reactions, Elsevier, New York, 1965; H. L. Holmes, Org. React., 1948, 4, 60.
2. J.-Y. Merour, A.-S. Bourlot and E. Desarbre, Tetrahedron Lett., 1995, 36, 3527; I. E. Marko, G. R. Evans, J.-P. Declercq, B. Tinant and J. Feneau-Dupont, Acros Organics Acta, 1995, 1, 2, 63; S. Danishefsky and M. Bednarski, J. Am. Chem. Soc., 1983, 105, 3716; S. Danishefsky and M. Bednarski, Tetrahedron Lett., 1984, 25, 721.
3. For preparation of ethyl (E)-4-oxobutenoate by ozonolysis of ethyl sorbate, see V. Tarik, L. A. Mitscher and J. K. Dep, Synthesis, 1980, 10, 807.
4. W. G. Dauben and H. O. Krabbenhoft, J. Org. Chem., 1977, 42, 282.