Polarizing the Nazarov Cyclization: Efficient Catalysis under Mild Conditions

Journal of the American Chemical Society

Volumn 125, Issue 47, 2003, Pages 14278-14279

  He, Wei ^a   Sun, Xiufeng ^a   Frontier, Alison J ^a  

^a UNIVERSITY OF ROCHESTER   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ARTICLE; CATALYSIS; CYCLIZATION; ELIMINATION REACTION; ENANTIOSELECTIVITY; MOLECULAR STABILITY; NAZAROV CYCLIZATION; POLARIZATION; REACTION OPTIMIZATION; SUBSTITUTION REACTION;

EID: 0344443373     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja037910b     Document Type: Article

References (32)

1. For reviews, see: (a) Habermas, K. L.; Denmark S. E.; Jones, T. K. Org. React. 1994, 45, 1.
2. (b) Santelli-Rouvier, C.; Santelli, M. Synthesis 1983, 429.
3. Sequences involving Nazarov cyclization followed by trapping or reduction of the intermediate cation have been developed by West: (a) Zuev, D.; Paquette, L. A. Chemtracts 1999, 12, 1019.
4. (b) Giese, S.; Kastrup, L.; Stiens, D.; West, F. G. Angew. Chem., Int. Ed. 2000, 39, 1970.
5. (c) Browder, C. C.; Marmsater, F. P.; West, F. G. Org. Lett. 2001, 3, 3033.
6. (d) Giese, S.; West, F. G. Tetrahedron 2000, 56, 10221.
7. (e) Wang, Y.; Schill, B. D.; Arif, A. M.; West, F. G. Org. Lett. 2003, 5, 2747.
8. For studies of the Nazarov cyclization of allenyl vinyl ketones, see: (a) Tius, M. A. Acc. Chem. Res. 2003, 36, 284, and references therein.
9. (b) Leclerc, E.; Tius, M. A. Org. Lett. 2003, 5, 1171.
10. (c) Bee, C.; Tius, M. A. Org. Lett. 2003, 5, 1681.
11. Woodward, R. B.; Hoffmann, R. The Conservation of Orbital Symmetry; Verlag Chemie: Weinheim, Germany, 1970; pp 38-64.
12. Houk, K. N. In Strain and Its Implications in Organic Chemistry; deMeijere, A., Blechert, S., Eds.; Kluwer Academic Publishers: Dodrecht, The Netherlands, 1989; pp 25-37.
13. 3 for β-silyl divinyl ketones).
14. 3SiH).
15. 2).
16. Denmark's β-silyl alkene, which suffer elimination with excellent regioselectivity, are an exception. Denmark, S. E.; Jones, T. K. J. Am. Chem. Soc. 1982, 104, 2642. Also see ref 1a and references therein.
17. For leading references for all four reaction types, see: (a) Catalytic Asymmetric Synthesis, 2nd ed.; Ojima, I., Ed.; Wiley-VCH: Weinheim, Germany, 2000; Chapter 8.
18. (b) Johnson, J. S.; Evans, D. A. Acc. Chem. Res. 2000, 33, 325.
19. This strategy has been used successfully for the development of highly reactive dienes for the Diels-Alder reaction: (a) Danishefsky, S. J. Acc. Chem. Res. 1981, 14, 400.
20. (b) Kozmin, S. A.; Janey, J. M.; Rawal, V. H. J. Org. Chem. 1999, 64, 3039.
21. α-Carboalkoxy divinyl ketones have been reported as highly reactive substrates that undergo regioselective elimination in Nazarov cyclizations with stoichiometric promoter: (a) Marino, J. P.; Lindermann, R. J. J. Org. Chem. 1981, 46, 3696.
22. (b) Andrews, J. F. P.; Regan, A. C. Tetrahedron Lett. 1991, 32, 7731.
23. (c) Kerr, D. J.; Metje, C.; Flynn, B. L. Chem. Commun. 2003, 1380. Until Flynn's recent report, yields were consistently low.
24. α-Heteroatom-substituted divinyl ketones have been found to be particularly reactive substrates in Nazarov cyclizations: Tius, M. A.; Kwok, C.-K.; Gu, X.-q.; Zhao, C. Synth. Commun. 1994, 24, 871.
25. For a study of the influence of divinyl ketone substituents on the silicon-directed Nazarov cyclization, see Denmark, S. E.; Habermas, K. L.; Hite, G. A. Helv. Chim. Acta 1988, 71, 168.
26. Synthesis of all α-carboalkoxy divinyl ketones was achieved by Knoevenagel condensation of a β-keto ester and an aldehyde, catalyzed by a secondary amine. Desimoni, G.; Faita, G.; Ricci, M.; Righetti, P. Tetrahedron 1998, 54, 9581. Most divinyl ketones were isolated as a single trisubstituted olefin and are drawn as the Z-isomer, but we have been unable to confidently assign the olefin geometry at this time.
27. When the catalyst was stirred with 2.5 mol % potassium carbonate before addition of substrate, the rate of cyclization was unchanged, ruling out adventitious catalysis by triflic acid. Reactions run under argon gave comparable results.
28. Support for the stereochemical assignments: The stereochemistry of representative β-ketoester 4b is stable under equilibrating conditions (NaOH/MeOH/THF/55 °C, 2h), trans stereochemistry was found to be thermodynamically favored for similar compounds reported in the literature (refs 7 and 10c), and trans stereochemistry of 3a was confirmed by an X-ray diffraction study.
29. The structure of 12a was determined by an X-ray diffraction study.
30. After submission, it was found that cyclization of 17f improved significantly when conducted in an inert atmosphere. This anomalous result will be examined carefully in due course.
31. Copper triflate probably coordinates to both carbonyl groups: (a) Evans, D. A.; Rovis, T.; Kozlowski, M. C.; Tedrow, J. S. J. Am. Chem. Soc. 1999, 121, 1994.
32. (b) Evans, D. A.; Scheidt, K. A.; Johnson, J. N.; Willis, M. C. J. Am. Chem. Soc. 2001, 123, 4480.