Heterogeneously catalyzed asymmetric C=C hydrogenation: Origin of enantioselectivity in the proline-directed Pd/isophorone system

Journal of the American Chemical Society

Volumn 128, Issue 22, 2006, Pages 7329-7334

  McIntosh, Alexander I ^a   Watson, David J ^a   Burton, Jonathan W ^a   Lambert, Richard M ^a  

^a UNIVERSITY OF CAMBRIDGE   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

CATALYSIS; ESTERS; ISOMERS; KINETIC ENERGY; PALLADIUM; REACTION KINETICS;

3,3,5-TRIMETHYLCYCLOHEXANONE (TMCH); ENANTIOSELECTIVITY; ISOPHORONE SYSTEM; METAL SURFACES;

HYDROGENATION;

ISOPHORONE; PALLADIUM; PLATINUM DERIVATIVE; PROLINE; TRANSITION ELEMENT;

ANALYTIC METHOD; ARTICLE; ASYMMETRIC CATALYSIS; CATALYSIS; CHIRALITY; ENANTIOMER; ENANTIOSELECTIVITY; HYDROGENATION; HYDROLYSIS; REACTION ANALYSIS;

EID: 33744939448     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja061104y     Document Type: Article

References (27)

1. Knowles, W. S. Angew. Chem., Int. Ed. 2002, 41, 1999-2007.
2. Noyori, R. Angew. Chem., Int. Ed. 2002, 41, 2008-2022.
3. Sharpless, K. B. Angew. Chem., Int. Ed. 2002, 41, 2024-2032.
4. Blaser, H. U.; Baiker, A. In Handbook of Heterogeneous Catalysis; Ertl, G., Knötzinger, H., Weitkamp, J., Eds.; Wiley-VCH: New York, 1997; Vol. 5, p 2422.
5. Blaser, H. U.; Jalett, H. P.; Muller, M.; Studer, M. Catal. Today 1997, 37, 441-463.
6. Baiker, A. J. Mol. Catal. A-Chem. 1997, 115, 473-493.
7. Wells, P. B.; Wilkinson, A. G. Top. Catal. 1998, 5, 39-50.
8. Jenkins, D. J.; Alabdulrahman, A. M. S.; Attard, G. A.; Griffin, K. G.; Johnston, P.; Wells, P. B. J. Catal. 2005, 234, 230-239.
9. Attard, G. A.; Ahmadi, A.; Jenkins, D. J.; Hazzazi, O. A.; Wells, P. B.; Griffin, K. G.; Johnston, P.; Gillies, J. E. ChemPhysChem 2003, 4, 123-130.
10. Bonello, J. M.; Williams, F. J.; Lambert, R. M. J. Am. Chem. Soc. 2003, 125, 2723-2729.
11. Bonello, J. M.; Lambert, R. M.; Kunzle, N.; Baiker, A. J. Am. Chem. Soc. 2000, 122, 9864-9865.
12. Jones, T. E.; Baddeley, C. J. Surf. Sci. 2002, 519, 237-249.
13. Jones, T. E.; Baddeley, C. J. Surf. Sci. 2002, 513, 453-467.
14. Jones, T. E.; Baddeley, C. J. J. Mol. Catal. A-Chem. 2004, 216, 223-231.
15. Lorenzo, M. O.; Baddeley, C. J.; Muryn, C.; Raval, R. Nature 2000, 404, 376-379.
16. Tungler, A.; Máthé, T.; Petró, J.; Tarnai, T. J. Mol. Catal. 1990, 61, 259-267.
17. Tungler, A.; Kajtár, M.; Máthé, T.; Tóth, G.; Fogassy, G.; Petró, J. Catal. Today 1989, 5, 159-171.
18. Flego, C.; Perego, C. Appl. Catal. A-Gen. 2000, 192, 317-329.
19. Nozaki, H.; Yamaguti, T.; Ueda, S.; Kondô, K. Tetrahedron 1968, 24, 1445-1453.
20. 21 An ammonium substituent therefore has little effect on the absorption wavelength of the conjugated system to which it is attached; hence the condensation product formed between praline and isophorone may be the zwitterionic species corresponding to 4.
21. Jaffé, H. H.; Orchin, M. Theory and Applications of Ultraviolet Spectroscopy; Wiley: New York, 1962.
22. Girard, C.; Kagan, H. B. Angew. Chem., Int. Ed. 1998, 37, 2923-2959.
23. Kagan, H. B.; Fiaud, J. C. Top. Stereochem. 1988, 18, 249.
24. Steps IV and V consume one molecule of L-proline and one molecule of isophorone, so the only limit to a high ee of (S)-TMCH is that the reaction is routinely run until only 1 equiv of H2 is consumed-step V just reduces the amount of (S)-TMCH which can be produced, not the ee of the TMCH which is controlled by hydrogen availability, that is, conversion.
25. Purification of the hydrogenation mixture from a τ = 72 h experiment which was halted at the turning point between regimes A and B gave a 13:1 mixture of 7:7′.
26. If the hydrogenation occurred in one surface-bound event, the two substituents on the cyclohexane in 7 would be cis and not trans to one another. The trans stereochemistry of the cyclohexane substituents in 7 is readily accounted for; hydrogenation of 8 will likely occur from the least hindered face of the enamine (or imine) double bond from the lowest energy conformer in which two of the three methyl groups are pseudoequatorial. (Diagram presented)
27. McIntosh, A. I.; Watson, D. J.; Lambert, R. M. Manuscript in preparation.