Stereoselective Cope Rearrangements of Syn- and Anti-Aldol Products

Synlett

Volumn 1996, Issue 3, 1996, Pages 212-214

  Schneider, Christoph ^a   Rehfeuter, Markus ^a  

^a UNIVERSITY OF GÖTTINGEN   (Germany)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0004582811     PISSN: 09365214     EISSN: None     Source Type: Journal    
DOI: 10.1055/s-1996-5369     Document Type: Article

References (28)

1. W. von E. Doering, W. R. Roth, Tetrahedron 1962, 18, 67.
2. R. K. Hill, N. W. Gilman, J. Chem. Soc., Chem. Commun. 1967, 619.
3. (a) R. K. Hill in Comprehensive Organic Synthesis, Vol. 5; B. M. Trost, I. Fleming, Ed.; Pergamon Press: Oxford, 1991; p 785;
4. (b) L. A. Paquette, Angew. Chem. 1990, 102, 642; Angew. Chem. Int. Ed. Engl. 1990, 29, 609.
5. (b) L. A. Paquette, Angew. Chem. 1990, 102, 642; Angew. Chem. Int. Ed. Engl. 1990, 29, 609.
6. P. Wipf in Comprehensive Organic Synthesis, Vol. 5; B. M. Trost, I. Fleming, Ed.; Pergamon Press: Oxford, 1991; p 827.
7. A notable exception are anionic oxy-Cope rearrangements, see: (a) D. A. Evans, A. M. Golob, J. Am. Chem. Soc. 1975, 97, 4765; (b) D. A. Evans, J. V. Nelson, J. Am. Chem. Soc 1980, 102, 774.
8. A notable exception are anionic oxy-Cope rearrangements, see: (a) D. A. Evans, A. M. Golob, J. Am. Chem. Soc. 1975, 97, 4765; (b) D. A. Evans, J. V. Nelson, J. Am. Chem. Soc 1980, 102, 774.
9. Pd-catalyzed Cope rearrangements proceed under mild reactions conditions as well, but usually give a mixture of isomers, see: L.E. Overman, Angew. Chem. 1984, 96, 565; Angew. Chem. Int. Ed. Engl. 1984, 23, 579 and references cited therein.
10. Pd-catalyzed Cope rearrangements proceed under mild reactions conditions as well, but usually give a mixture of isomers, see: L.E. Overman, Angew. Chem. 1984, 96, 565; Angew. Chem. Int. Ed. Engl. 1984, 23, 579 and references cited therein.
11. For investigations into the stereoselectivity of anionic oxy-Cope rearrangements of acyclic 1,5-dienes see: (a) K. Tomooka, S.-W. Wei, T. Nakai, Chem. Lett. 1991, 43; (b) S.-Y. Wei, K. Tomooka, T. Nakai, J. Org. Chem. 1991, 56, 5973; (c) L.A. Paquette, G.D. Maynard, J. Am. Chem. Soc. 1992, 114, 5018; (d) E. Lee, Y.R. Lee, B. Moon, O. Kwon, M.S. Shim, J.S. Yun, J. Org. Chem. 1994, 59, 1444.
12. For investigations into the stereoselectivity of anionic oxy-Cope rearrangements of acyclic 1,5-dienes see: (a) K. Tomooka, S.-W. Wei, T. Nakai, Chem. Lett. 1991, 43; (b) S.-Y. Wei, K. Tomooka, T. Nakai, J. Org. Chem. 1991, 56, 5973; (c) L.A. Paquette, G.D. Maynard, J. Am. Chem. Soc. 1992, 114, 5018; (d) E. Lee, Y.R. Lee, B. Moon, O. Kwon, M.S. Shim, J.S. Yun, J. Org. Chem. 1994, 59, 1444.
13. For investigations into the stereoselectivity of anionic oxy-Cope rearrangements of acyclic 1,5-dienes see: (a) K. Tomooka, S.-W. Wei, T. Nakai, Chem. Lett. 1991, 43; (b) S.-Y. Wei, K. Tomooka, T. Nakai, J. Org. Chem. 1991, 56, 5973; (c) L.A. Paquette, G.D. Maynard, J. Am. Chem. Soc. 1992, 114, 5018; (d) E. Lee, Y.R. Lee, B. Moon, O. Kwon, M.S. Shim, J.S. Yun, J. Org. Chem. 1994, 59, 1444.
14. For investigations into the stereoselectivity of anionic oxy-Cope rearrangements of acyclic 1,5-dienes see: (a) K. Tomooka, S.-W. Wei, T. Nakai, Chem. Lett. 1991, 43; (b) S.-Y. Wei, K. Tomooka, T. Nakai, J. Org. Chem. 1991, 56, 5973; (c) L.A. Paquette, G.D. Maynard, J. Am. Chem. Soc. 1992, 114, 5018; (d) E. Lee, Y.R. Lee, B. Moon, O. Kwon, M.S. Shim, J.S. Yun, J. Org. Chem. 1994, 59, 1444.
15. Cope rearrangements of aldol products have not been reported to our knowledge. In their work on Reformatsky reactions of γ-bromocrotonic esters with α,β-unsaturated carbonyl compounds Hudlicky et al. discuss the Cope rearrangement as a possible explanation for the conversion of the 1,2-α-products to the 1,4-γ-products under thermodynamic conditions, see: (a) T. Hudlicky, M.G. Natchus, L.D. Kwart, B.L. Colwell, J. Org. Chem. 1985, 50, 4300; (b) R.L. Fan, T. Hudlicky, Tetrahedron Lett. 1989, 30, 5533.
16. Cope rearrangements of aldol products have not been reported to our knowledge. In their work on Reformatsky reactions of γ-bromocrotonic esters with α,β-unsaturated carbonyl compounds Hudlicky et al. discuss the Cope rearrangement as a possible explanation for the conversion of the 1,2-α-products to the 1,4-γ-products under thermodynamic conditions, see: (a) T. Hudlicky, M.G. Natchus, L.D. Kwart, B.L. Colwell, J. Org. Chem. 1985, 50, 4300; (b) R.L. Fan, T. Hudlicky, Tetrahedron Lett. 1989, 30, 5533.
17. D.A. Evans, E.B. Sjogren, J. Bartroli, R.L. Dow, Tetrahedron Lett. 1986, 27, 4957.
18. H.C. Brown, K. Ganesàm, R.K. Dhar, J. Org. Chem. 1993, 58, 147.
19. D.A. Evans, J.V. Nelson, T.R. Taber, Top. Stereochem. 1982, 13, 1.
20. All compounds are racemic mixtures, for simplicity only one enantiomer is shown.
21. 3), 25.28 (thexyl-C), 32.24 (C-5′), 34.00 (thexyl-CH), 40.86 (C-4′), 42.65 (C-4), 61.96 (C-5), 116.2 (C-6′), 120.9 (C-2′), 139.7 (C-7′), 150.2 (C-3′), 153.4 (C-2), 165.0 (C-1′); MS (70 eV): m/z = 282 (84), 212 (24), 195 (54), 144 (63), 129 (100), 73 (72).
22. J. Hine, N.W. Flachskam, J. Am. Chem. Soc. 1973, 95, 1179.
23. The isomerically pure Cope products were submitted to the reaction conditions again without any isomerization. Varying the reaction time between 30 min and 6 h did not affect the product ratio either.
24. C. L. Perrin, D. J. Faulkner, Tetrahedron Lett. 1969, 10, 2783.
25. (a) H.O. House, V. Kramar, J. Org. Chem. 1963, 28, 3362;
26. (b) G.W. Spears, C.E. Caufield, W.C. Still, J. Org. Chem. 1987, 52, 1226.
27. (a) D.A. Evans, J. Bartroli, T.L. Shih, J. Am. Chem. Soc. 1981, 103, 2128;
28. (b) D.A. Evans, Aldrichimica Acta 1982, 15, 23.