An approach to the C(17)–C(24) fragment of bryostatins: applications of stereoselective trisubstituted alkene formation by palladium(0) catalysed coupling of enol acetates and vinylic bromides

Abstract

The enol acetate 26 couples stereospecifically with the vinylic bromides 25 and 29 in the presence of tributyltin methoxide and a catalytic amount of dichlorobis(tri-o-tolylphosphine)palladium to give the βγ-unsaturated ketones 27 and 30 with retention of double-bond position and geometry. The βγ-unsaturated ketone 42 which has stereochemistry and functionality corresponding to the C(17)–C(24) fragment of the C(20)-deoxybryostatins, is similarly prepared from the enol acetate 26 and the vinylic bromide 41 and can be deprotected to give the hydroxyketone 43.

References

1. G. R. Pettit, Progress in the Chemistry of Natural Products, Springer-Verlag, New York, 1991, vol. 57, p. 157.
2. M. A. Blanchette, M. S. Malamas, M. H. Nantz, J. C. Roberts, P. Somfrai, D. C. Whritenour and S. Masamune, J. Org. Chem., 1989, 54, 2817; R. Roy and A. W. Rey, Synlett, 1990, 448; D. A. Evans, J. A. Gauchet-Prunet, E. M. Carreira and A. B. Charette, J. Org. Chem., 1991, 56, 741; J. De Brabander, K. Vanhessche and M. Vandewalle, Tetrahedron Lett., 1991, 32, 2821; K. Ohmori, T. Suzuki, K. Miyazawa, S. Nishiyama and S. Yamamura, Tetrahedron Lett., 1993, 34, 4981; R. W. Hoffmann and H. C. Stiasny, Tetrahedron Lett., 1995, 36, 4595; M. Kalesse and M. Eh, Tetrahedron Lett., 1996, 37, 1767; T. F. J. Lampe and H. M. R. Hoffmann, Chem. Commun., 1996, 1931; D. A. Evans and E. M. Carreira, Tetrahedron Lett., 1990, 31, 4703; T. F. J. Lampe and H. M. R. Hoffmann, Tetrahedron Lett., 1996, 37, 7695; R. Roy, A. W. Rey, M. Charron and R. Molino, J. Chem. Soc., Chem. Commun., 1989, 1308; R. Roy and A. W. Rey, Can. J. Chem., 1991, 69, 62; K. J. Hale, J. A. Lennon, S. Manaviazar, M. H. Javaid and C. J. Hobbs, Tetrahedron Lett., 1995, 36, 1359; K. Ohmori, S. Nishiyama and S. Yamamura, Tetrahedron Lett., 1995, 36, 6519; K. Ohmori, T. Suzuki, S. Nishiyama and S. Yamamura, Tetrahedron Lett., 1995, 36, 6515; 68, 715; J. De Brabander, B. A. Kulkarni, R. Garcia-Lopez and M. Vandewalle, Tetrahedron: Asymmetry, 1997, 8, 1721.
3. M. Kageyama, T. Tamura, M. H. Nantz, J. C. Roberts, P. Somfrai, D. C. Whritenour and S. Masamune, J. Am. Chem. Soc., 1990, 112, 7407; S. Masamune, Pure Appl. Chem., 1988, 60, 1587.
4. R. J. Maguire, S. P. Munt and E. J. Thomas, J. Chem. Soc., Perkin Trans. 1, 1998, 2853.
5. J. De Brabander and M. Vandewalle, Synlett, 1994, 231; J. De Brabander and M. Vandewalle, Synthesis, 1994, 855; J. De Brabander and M. Vandewalle, Pure Appl. Chem., 1996, 68, 715.
6. H. Kashihara, H. Shinoki, H. Suemune and K. Saki, Chem. Pharm. Bull., 1986, 34, 4527; D. Seebach and H. Meyer, Angew. Chem., 1974, 86, 40.
7. C. J. Kowalski and K. W. Fields, J. Org. Chem., 1981, 46, 197.
8. I. Paterson and I. Fleming, Tetrahedron Lett., 1979, 20, 995; I. Paterson and I. Fleming, Tetrahedron Lett., 1979, 20, 2179.
9. H. Nagaoka and Y. Kishi, Tetrahedron, 1981, 37, 3873; E. J. Corey and P. L. Fuchs, Tetrahedron Lett., 1972, 13, 3769.
10. M. Kosugi, I. Hagiwara, T. Sumiya and T. Migita, Bull. Chem. Soc. Jpn., 1984, 57, 242.
11. H. X. Zhang, F. Guibé and G. Balavoine, J. Org. Chem., 1990, 55, 1857; C. B. Ziegler, Jr. and R. F. Heck, J. Org. Chem., 1978, 43, 2941; P. Four and F. Guibé, J. Org. Chem., 1981, 46, 4439.
12. S.-M. L. Chen, R. E. Schaub and C. V. Grudzinskas, J. Org. Chem., 1978, 43, 3450.
13. H. O. House and V. Kramar, J. Org. Chem., 1963, 28, 3362.
14. J. E. Baxter, E. Mata and E. J. Thomas, Tetrahedron, 1998, in press.
15. J. A. Frick, J. B. Klassen, A. Bathe, J. M. Abramson and H. Rapoport, Synthesis, 1992, 621.
16. S. Takano, Y. Sekiguchi, N. Sato and K. Ogasawara, Synthesis, 1987, 139.
17. E. Piers, M. J. Chong and H. E. Morton, Tetrahedron, 1989, 45, 363; P. Angers and P. Canonne, Tetrahedron Lett., 1995, 36, 2397; E. Piers and H. E. Morton, J. Chem. Soc., Chem. Commun., 1978, 1033; E. Piers and H. E. Morton, J. Org. Chem., 1980, 45, 4263; E. Piers, J. M. Chong and H. E. Morton, Tetrahedron Lett., 1981, 22, 4905.
18. T. Tsunoda, M. Suzuki and R. Noyori, Tetrahedron Lett., 1980, 21, 1357; R. Noyori, S. Murata and M. Suzuki, Tetrahedron, 1981, 37, 3899.
19. D. D. Perrin, W. L. F. Armarego and D. R. Perrin, Purification of Laboratory Chemicals, 4th edn., Pergamon Press, Oxford, 1980.
20. H. O. House, L. J. Czuba, M. Gall and H. D. Olmstead, J. Org. Chem., 1969, 34, 2324.
21. C. Ainsworth, F. Chen and Y.-N. Kuo, J. Organomet. Chem., 1972, 46, 59.