Tropos or Atropos nature of rhodium complexes bearing a tetrakis(phosphanyl)terphenyl ligand: Highly enantioselective catalysis of ene-type cyclization

Organic Letters

Volumn 7, Issue 26, 2005, Pages 5777-5780

  Mikami, Koichi ^a   Kataoka, Shohei ^a   Aikawa, Kohsuke ^a  

^a TOKYO INSTITUTE OF TECHNOLOGY   (Japan)

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Indexed keywords

EID: 30344438555     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol052281r     Document Type: Article

References (28)

1. Jacobsen, E. N.; Pfaltz, A.; Yamamoto, H. Comprehensive Asymmetric Catalysis; Springer: Berlin, 1999; Vols. 1-3.
2. (a) Mikami, K.; Aikawa, K.; Yusa, Y.; Jodry, J. J.; Yamanaka, M. Synlett 2002, 10, 1561-1578. Oki has discussed the borderline between tropos and atropos nature. A half-life of 1000 s (16.7 min) is considered as the minimum requirement for atropos biphenyl. The free energy of activation is necessary more than ca. 22.3 kcal/mol (93.2 kJ/mol) to isolate it at room temperature (300 K):
3. (b) Oki, M.; Yamamoto, G. Bull. Chem. Soc. Jpn. 1971, 44, 266-270.
4. (c) Oki, M. Top. Stereochem. 1983, 14, 1-81.
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6. (b) Desponds, O.; Schlosser, M. J. Organomet. Chem. 1996, 507, 257-261.
7. For the BIPHEP-Rh complex: (a) Mikami, K.; Kataoka, S.; Yusa, Y.; Aikawa, K. Org. Lett. 2004, 6, 3699-3701.
8. For the BIPHEP-Ru complex: (b) Mikami, K.; Korenaga, T.; Terada, M.; Ohkuma, T.; Pham, T.; Noyori, R. Angew. Chem., Int. Ed. 1999, 38, 495-497.
9. (c) Mikami, K.; Aikawa, K.; Korenaga, T. Org. Lett. 2001, 3, 243-245.
10. For the BIPHEP-Pd complex: (d) Mikami, K.; Aikawa, K.; Yusa, Y.; Hatano, M. Org. Lett. 2002, 4, 91-94.
11. (e) Mikami, K.; Aikawa, K.; Yusa, Y. Org. Lett. 2002, 4, 95-97.
12. For the BIPHEP-Pt complex: (f) Tudor, M. D.; Becker, J. J.; White, P. S.; Gagne, M. R. Organometallics 2000, 19, 4376-4484.
13. (g) Becker, J. J.; White, P. S.; Gagne, M. R. J. Am. Chem. Soc. 2001, 123, 9478-9479.
14. (h) Mikami, K.; Kakuno, H.; Aikawa, K. Angew. Chem., Int. Ed. 2005, in press.
15. For the use of different chirally flexible (tropos) NUPHOS ligands, see: (i) Doherty, S.; Newman, C. R.; Rath, R. K.; Luo, H.; Nieuwenhuyzen, M.; Knight, J. G. Org. Lett. 2003, 5, 3863-3866.
16. (j) Doherty, S.; Knight, J. K.; Hardacre, C.; Lou, H.; Newman, C. R.; Rath, R. K.; Campbell, S.; Nieuwenhuyzen, M. Organometallics 2004, 23, 6127-6133.
17. (a) Schmuck, C. Angew. Chem., Int. Ed. 2003, 42, 2448-2452.
18. (b) Urbano, A. Angew. Chem., Int. Ed. 2003, 42, 3986-3989.
19. Aikawa, K.; Mikami, K. Angew. Chem., Int. Ed. 2003, 42, 5458-5461.
20. For the BINAP-Rh complex: (a) Takaya, H.; Miyashita, A.; Souchi, T.; Noyori, R. Tetrahedron 1984, 40, 1245-1253.
21. (b) Halpern, J.; Rily, D. P.; Chan, A. S. C.; Pluth, J. J. J. Am. Chem. Soc. 1977, 8055-8057.
22. The single diastereomer (M)/(R)/(R)-2 could also be obtained at 80 °C in dichloroethane for 30 min.
23. (a) Cao, P.; Zhang, Xumu Angew. Chem., Int. Ed. 2000, 39, 4104-4106.
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28. 2 (0.01 mmol) and (R)-DABN (0.021 mmol) in a 10 mL Schlenk tube was added dry dichloroethane (0.70 mL) under Ar atmosphere. The mixture was frozen and charged with hydrogen gas using a balloon (1 atm) and then stirred for 30 min at room temperature. After being charged with argon atmosphere once more, the mixture was stirred at 80°C for 30 min and then cooled to 5°C. 1,6-Enyne substrate 4 (0.2 mmol) and TfOH (0.04 mmol) were added, and the reaction mixture was stirred at 5°C for 3 h and directly loaded onto a silica gel column to give cyclic product as a colorless oil (yield 92%). The enantiomeric excess (% ee) was determined by GC analysis (99% ee).