All-carbon quaternary stereogenic centers by enantioselective Cu-catalyzed conjugate additions promoted by a chiral N-heterocyclic carbene

Angewandte Chemie - International Edition

Volumn 46, Issue 7, 2007, Pages 1097-1100

  Brown, M Kevin ^a   May, Tricia L ^a   Baxter, Carl A ^a   Hoveyda, Amir H ^a  

^a BOSTON COLLEGE   (United States)

Author keywords

Asymmetric catalysis; Asymmetric synthesis; Carbenes; Conjugate addition; Quaternary centers

Indexed keywords

ADDITION REACTIONS; CATALYST ACTIVITY; CHIRALITY; ENANTIOSELECTIVITY; ESTERS; SYNTHESIS (CHEMICAL);

ASYMMETRIC CATALYSIS; CARBENES; CONJUGATE ADDITION; QUATERNARY CENTERS;

UNSATURATED COMPOUNDS;

CARBENE; CARBON; COPPER; DRUG DERIVATIVE; HYDROCARBON; METHANE; ORGANOMETALLIC COMPOUND;

ARTICLE; CATALYSIS; CHEMISTRY; STEREOISOMERISM; X RAY CRYSTALLOGRAPHY;

CARBON; CATALYSIS; COPPER; CRYSTALLOGRAPHY, X-RAY; HYDROCARBONS; METHANE; ORGANOMETALLIC COMPOUNDS; STEREOISOMERISM;

EID: 34247201978     PISSN: 14337851     EISSN: None     Source Type: Journal    
DOI: 10.1002/anie.200604511     Document Type: Article

References (30)

1. J. Christophers, A. Baro (Eds.), Quaternary Stereocenters: Challenges and Solutions for Organic Synthesis, Wiley-VCH, Weinheim, 2006.
2. a) N. Krause, A. Hoffmann-Röder, Synthesis 2001, 171-196;
3. b) A. Alexakis, C. Benhaim, Eur. J. Org. Chem. 2002, 3221-3236;
4. c) B. L. Feringa, R. Naasz, R. Imbos, L. A. Arnold in Modern Organocopper Chemistry (Ed.: N. Krause), Wiley-VCH, Weinheim, 2002, pp. 224-258.
5. For previous studies regarding Cu-catalyzed ACA to afford all-carbon quaternary stereogenic centers, see: a) J. Wu, D. Mampreian, A. H. Hoveyda, J. Am. Chem. Soc. 2005, 127, 4584-4585;
6. b) A. W. Hird, A. H. Hoveyda, J. Am. Chem. Soc. 2005, 127, 14988-14989;
7. c) M. d'Augustin, L. Palais, A. Alexakis, Angew. Chem. 2005, 117, 1400-1402;
8. Angew. Chem. Int. Ed. 2005, 44, 1376-1378;
9. d) P. Mauleon, J. C. Carretero, Chem. Commun. 2005, 4961-4963;
10. e) E. Fillion, A. Wilsily, J. Am. Chem. Soc. 2006, 128, 2774-2775;
11. f) R. Shintani, W.-L. Duan, T. Hayashi, J. Am. Chem. Soc. 2006, 128, 5628-5629;
12. g) K. Lee, M. K. Brown, A. W. Hird, A. H. Hoveyda, J. Am. Chem. Soc. 2006, 128, 7182-7184;
13. h) D. Martin, S. Kehrli, M. d'Augustin, H. Clavier, M. Mauduit, A. Alexakis, J. Am. Chem. Soc. 2006, 128, 8416-8417.
14. For Cu-catalyzed asymmetric allylic alkylations that afford all-carbon quaternary stereogenic centers, see: a) M. A. Kacprzynski, A. H. Hoveyda, J. Am. Chem. Soc. 2004, 126, 10676-10681;
15. b) A. O. Larsen, W. Leu, C. Nieto-Oberhuber, J. E. Campbell, A. H. Hoveyda, J. Am. Chem. Soc. 2004, 126, 11130-11131;
16. c) J. J. Van Veldhuizen, J. E. Campbell, R. E. Giudici, A. H. Hoveyda, J. Am. Chem. Soc. 2005, 127, 6877-6882;
17. for NHC-catalyzed asymmetric allylic alkylations with alkyl Grignard reagents, see: d) Y. Lee, A. H. Hoveyda, J. Am. Chem. Soc. 2006, 128, 15604-15605.
18. For examples of Cu-catalyzed enantioselective reactions that deliver all-carbon quaternary stereogenic centers and involve catalysts bearing a chiral NHC, see references [3g,h] and [4b,c].
19. 6; 80°C). The chiral imidazolium salt is prepared in four steps from commercially available starting materials. See the Supporting Information for all details.
20. For details regarding the proof of the stereochemical identities of catalytic ACA products, see the Supporting Information.
21. On the basis of steric considerations, it is likely that it is the derived monomeric chiral NHC complexes that serve as active catalysts; also see reference [3g].
22. We are grateful to K.-s. Lee for carrying out these experiments. Details will be disclosed in a separate account.
23. K. Li, A. Alexakis, Angew. Chem. 2006, 118, 7762-7765;
24. Angew. Chem. Int. Ed. 2006, 45, 7600-7603.
25. For functionalization of enolates derived from catalytic ACA reactions, see: O. Knopff, A. Alexakis, Org. Lett. 2002, 4, 3835-3837.
26. a) D. Peña, F. López, S. R. Harutyunyan, A. J. Minnaard, B. L. Feringa, Chem. Commun. 2004, 1836-1837;
27. b) J. G. Kim, P. J. Walsh, Angew. Chem. 2006, 118, 4281-4284;
28. Angew. Chem. Int. Ed. 2006, 45, 4175-4178.
29. For a review regarding synthesis, catalytic activity, and structural characteristics of NHC complexes, see: J. C. Garrison, W. J. Youngs, Chem. Rev. 2005, 105, 3978-4008.
30. For an enantioselective NHC-catalyzed protocol that affords all-carbon quaternary stereogenic centers, see: M. S. Kerr, T. Rovis, J. Am. Chem. Soc. 2004, 126, 8876-8877.