Useful Enantioselective Bicyclization Reactions Using an N-Protonated Chiral Oxazaborolidine as Catalyst

Organic Letters

Volumn 5, Issue 21, 2003, Pages 3979-3982

  Zhou, Gang ^a   Hu, Qi Ying ^a   Corey, E J ^a  

^a HARVARD UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ALDEHYDE; ALKENE DERIVATIVE; DECANE; OXAZABOROLIDINE DERIVATIVE;

ARTICLE; BICYCLIZATION; CATALYST; CHEMICAL REACTION; CHIRALITY; CYCLOADDITION; DIELS ALDER REACTION; ENANTIOSELECTIVITY; PROTON TRANSPORT;

EID: 0242543438     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol035542a     Document Type: Article

References (22)

1. Corey, E. J.; Shibata, T.; Lee, T. W. J. Am. Chem. Soc. 2002, 124, 3808-3809.
2. Ryu, D. H.; Lee, T. W.; Corey, E. J. J. Am. Chem. Soc. 2002, 124, 9992-9993.
3. Ryu, D. H.; Corey, E. J. J. Am. Chem. Soc. 2003, 125, 6388-6390.
4. Corey, E. J. Angew. Chem., Int. Ed. 2002, 41, 1650-1667.
5. 1 involves formyl C-H-O hydrogen bonding and π-π attractive interaction between the coordinated α,β-enal and the proximate C-aryl substituent in 1. See: Corey E. J. ; Lee, T. W. J. Chem. Soc., Chem. Commun. 2001, 1321-1329.
6. 2 involves α-C-H-O hydrogen bonding and π-π attractive interaction between the coordinated dienophile and the proximate C-aryl substituent in 1.
7. Ishihara, K.; Kurihara, H.; Yamamoto, H. J. Am. Chem. Soc. 1996, 118, 3049-3050.
8. Furuta, K.; Kanemitsu, A.; Yamamoto, H.; Takaoka, S. Tetrahedron Lett. 1989, 30, 7231-7232.
9. In addition, several examples have been recorded of catalytic enantioselective intramolecular Diels-Alder reactions with N-acyloxazolidinone/ trienes as reactants. See: (a) Iwasawa, N.; Sugimori, J.; Kawase, Y.; Narasaka, K. Chem. Lett. 1989, 1947-1950. (b) Evans, D. A.; Johnson, J. S. J. Org. Chem. 1997, 62, 786-787.
10. In addition, several examples have been recorded of catalytic enantioselective intramolecular Diels-Alder reactions with N-acyloxazolidinone/ trienes as reactants. See: (a) Iwasawa, N.; Sugimori, J.; Kawase, Y.; Narasaka, K. Chem. Lett. 1989, 1947-1950. (b) Evans, D. A.; Johnson, J. S. J. Org. Chem. 1997, 62, 786-787.
11. 3).
12. 5
13. See, for example: (a) Roush, W. R.; Gillis, H. R.; Ko, A. I. J. Am. Chem. Soc. 1982, 104, 2269-2283. (b) Wullf, W. D.; Powers, T. S. J. Org. Chem. 1993, 58, 2381-2393.
14. See, for example: (a) Roush, W. R.; Gillis, H. R.; Ko, A. I. J. Am. Chem. Soc. 1982, 104, 2269-2283. (b) Wullf, W. D.; Powers, T. S. J. Org. Chem. 1993, 58, 2381-2393.
15. 3).
16. 3); see, Evans, D. A.; Chapman, K. T.; Bisaha, J. J. Am. Chem. Soc. 1988, 110, 1238-1256.
17. The exo/endo ratio and the enantioselectivity were determined by GC analysis using a J&W Scientific Cyclosil-B column (30 m x 0.25 mm, 120°C, 25 psi), retention times: 21.99 min (exo, minor), 25.00 min (exo, major), 27.33 min (endo, minor), 28.28 min (endo, major). The absolute configuration of 9 was assigned by analogy with 3b and 3c.
18. 2AlCl-catalyzed cyclization of 10 by: Chen, C.-Y.; Hart; D. J. J. Org. Chem. 1993, 58, 3840-3849.
19. 1H NMR/NOE data. The exo/endo ratio and enantioselectivity were determined by GC analysis of the desilylation product 15 using a J&W Scientific Cyclosil-B column (30 m x 0.25 mm, 150°C, 25 psi), retention times: 16.29 min (exo), 16.88 min (exo), 17.71 min (endo, major), 18.63 min (endo, minor). The absolute configuration was determined by chemical correlation, as described.
20. The exo/endo ratio and the enantioselectivity were determined by GC analysis using a J&W Scientific Cyclosil-B column (30 m x 0.25 mm, 135°C, 25 psi), retention times: 36.33 min (exo), 37.26 min (exo), 41.28 min (endo, major), 41.70 min (endo, minor). The absolute configuration was assigned from the dextrorotation of 18 and also by analogy with dextrorotatory ketone 15.
21. 2, freshly prepared, 667 μL, 0.133 mmol). After 10-15 min at -20°C, a colorless homogeneous solution of cationic catalyst 1 was obtained.
22. -1.