Catalytic asymmetric vinylation of ketone enolates

Organic Letters

Volumn 3, Issue 12, 2001, Pages 1897-1900

  Chieffi, André ^a   Kamikawa, Ken ^a   Åhman, Jens ^a   Fox, Joseph M ^a   Buchwald, Stephen L ^a  

^a MASSACHUSETTS INSTITUTE OF TECHNOLOGY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

KETONE; VINYL DERIVATIVE;

ARTICLE; CATALYSIS; CHEMISTRY;

CATALYSIS; KETONES; VINYL COMPOUNDS;

EID: 0035859320     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol0159470     Document Type: Article

References (32)

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2. For a racemic version, see: (a) Palucki, M.; Buchwald, S. L. J. Am. Chem. Soc. 1997, 119, 11108.
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6. (e) Kawatsura, M.; Hartwig, J. F. J. Am. Chem. Soc. 1999, 121, 1473. For catalytic intramolecular vinylations of ketones, see:
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13. Ligands 2a-2c were prepared in several steps from (rac)-2, 2′-dibromo-1.1′-binaphthyl. Ligands 2d-2f were prepared in several steps from (R)-(+)-2,2′-diiodo-1,1′-binaphthyl. Ligand 2a has recently been used in catalytic asymmetric Suzuki couplings to give axially chiral biaryls: Yin, J.; Buchwald, S. L. J. Am. Chem. Soc. 2000, 122, 12051.
14. Three groups have prepared optically pure 2b by methods different than the one reported here: (a) Vyskočil, S.; Smrčina, M.; Hanuš, V.; Polášek, P.; Kočovský, P. J. Org. Chem. 1998, 63, 7738.
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17. (c) Ding, K.; Wang, Y.; Yun, H.; Liu, J.; Wu, Y.; Terada, M.; Okubo, Y.; Mikami, K. Chem. Eur. J. 1999, 5, 1734. In addition, the racemic form of 2a was reported: 216th Meeting of the American Chemical Society, August 23-27. 1998, Buchwald, S. L.; Wagaw, S.; Yang B. H. ORGN-004. For applications of 2b, see:
18. (d) Kočovský, P.; Vyskočil, Š.; Cířosavá, I.; Sejbal, J.; Tišlerová, I.; Smrčina, M.; Lloyd-Jones, G. C.; Stephen, S. C.; Butts, C. P.; Murray, M.; Langer, V. J. Am. Chem. Soc. 1999, 121, 7714.
19. (e) Kočovský, P.; Malkov, A.; Vyskočil, S.; Lloyd-Jones, G. C. Pure Appl. Chem. 1999, 71, 1425.
20. (f) Lloyd-Jones, G. C.; Stephen, S. C.; Murray, M.; Butts, C. P.; Vyskočil, Š.; Kočovský, P. Chem. Eur. J. 2000, 6, 4348.
21. For the Pd-catalyzed asymmetric alkylation of ketone enolates: (a) Trost, B. M.; Schroeder, G. M. J. Am. Chem. Soc. 1999, 121, 6759.
22. (b) You, S.-L.; Hou, X.-L.; Dai, L.-X.; Zhu, X.-Z. Org. Lett. 2001, 3, 149.
23. 2-Methyl-5-(N-methyl-anilinomethylene)cyclopentanone was prepared in 82% yield by the Claisen condensation of 2-methylcyclopentanone with ethyl formate followed by reaction with N-methylaniline.
24. 4, filtered, and concentrated. Chromatography gave 242 mg (95%) of the desired compound, which was judged to be 90% ee by chiral HPLC analysis.
25. 2 in toluene.
26. For the reaction at room temperature, neither the yield nor the enantioselectivity of the reaction is very sensitive to the Pd:L ratio; the same result was obtained using ratios of 1/1.25, 1/2, or 1/3.
27. The lower yields of 6c and 6d are due to difficulties during the isolation and purification steps due to their high volatility.
28. For a review on the preparation of chiral quaternary centers, see: Fuji, K. Chem. Rev. 1993, 93, 2037.
29. 2S, 6a and 6b gave (+)-2-formyl-2-methylcyclpentanone. Subsequent reaction with trimethylphosphono acetate/ NaH gave (+)-2-methyl-2-(2-trans-methoxycarbonyl-1-ethenyl)cyclopentanone, which is known to have the (R)-configuration. See: (a) Tori, M.; Miyake, T.; Hamaguchi, T.; Sono, M. Tetrahedron Asymmetry 1997, 8, 2731.
30. (b) Pfau, M.; Revial, G.; Guingant, A.; d'Angelo, J. J. Am. Chem. Soc. 1985, 107, 273.
31. 1 substituent of ligands 2 can dramatically alter the enantioselectivity is further illustrated by the low ee that is obtained with ligand 2f. Unfortunately, our efforts to prepare the isopropyl analogue of these ligands (which would be similar to 2a in terms of sterics) have thus far been unsuccessful.
32. For the use of chiral monodentate phosphine MOP-ligands in asymmetric catalysis: (a) Hayashi, T. Acc. Chem. Res. 2000, 33, 354.