Enantioselective reduction of ketones. Examination of bifunctional ligands

Tetrahedron Letters

Volumn 40, Issue 13, 1999, Pages 2477-2480

  Sibi, Mukund P ^a   Cook, Gregory R ^a   Liu, Pingrong ^a  

^a NORTH DAKOTA STATE UNIVERSITY   (United States)

Author keywords

Bifunctional ligands; Enantioselective reduction; Oxazaborolidines

Indexed keywords

KETONE; LIGAND;

ARTICLE; CHEMICAL ANALYSIS; CHEMICAL MODIFICATION; CHEMICAL REACTION; CHEMICAL STRUCTURE; DERIVATIZATION; ENANTIOMER; MOLECULAR MODEL; REACTION ANALYSIS; STRUCTURE ACTIVITY RELATION; STRUCTURE ANALYSIS;

EID: 0033605909     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(99)00281-6     Document Type: Article

References (27)

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3. (c) Fields, L. B.; Jacobsen, E. N. Tetrahedron: Asymmetry 1993, 4, 2229.
4. (d) Ward, J.; Börner, A.; Kagan, H. B. Tetrahedron: Asymmetry 1992, 3, 849.
5. (e) Börner, A.; Ward, J.; Kortus, K.; Kagan, H. B. Tetrahedron: Asymmetry 1993, 4, 2219.
6. (f) Kimmich, B. F. M.; Landis, C. L.; Powell, D. R. Organometallics 1996, 15, 4141.
7. (g) Williams, D. R.; Fromhold, M. G. Synlett 1997, 523.
8. For a comprehensive and excellent recent review see (a) Corey, E. J.; Helal, C. Angew. Chem. Int. Ed. Engl. 1998, 37, 1986.
9. (b) Itsuno, S.; Sakurai, Y.; Ito, K.; Hirao, A.; Nakashama, S. Bull. Chem. Soc. Jpn. 1987, 60, 395.
10. (c) Corey, E. J.; Bakshi, R. K.; Shibata, S. J. Am. Chem. Soc. 1987, 109, 5551.
11. (d) Corey, E. J.; Bakshi, R. K.; Shibata, S.; Chen, C.-P.; Singh, V. K. J. Am. Chem. Soc. 1987, 109, 7925.
12. (a) Senanayake, C. H. Aldrichimica Acta, 1998, 31, 3.
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14. (c) Hong, Y.; Gao, Y.; Nie, X.; Zepp, C. M. Tetrahedron Lett. 1994, 35, 6631.
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16. (d) Didier, E.; Loubinoux, B.; Tombo, G. M. R.; Rihs, G. Tetrahedron 1991, 47, 4941.
17. (a) Ref. 3c.
18. (b) Burns, B.; King, N. P.; Tye, H.; Studley, J. R.; Gamble, M.; Wills, M. J. Chem. Soc, Perkin Trans 1 1998, 1027.
19. (c) Gamble, M. P.; Smith, A. R.; Wills, M. J. Org. Chem. 1998, 63, 6068.
20. Ligands 2-7 were prepared starting from 1, and ligand 8 was synthesized from norephedrine by standard reaction sequences and they showed analytical characteristics consistent with their structure.
21. Ref. 3a,b, and c.
22. These reactions are unoptimized. We have tried a few other reaction conditions and solvents with all the modified ligands and the results in Table are the best at the present stage.
23. 3·DMS in THF gave the alcohol in87% chemical yield and 58% ee.
24. 3·DMS in THF gave the alcohol in87% chemical yield and 58% ee.
25. 3·DMS in THF gave the alcohol in87% chemical yield and 58% ee.
26. 3·DMS (2M in THF, 1.0 mmol) was added. After stirring for an additional 1.5 h at 40 °C, a solution of acetophenone (1.0 mmol in 1 mL THF) was added over 2 h using a syringe pump. The reaction was monitored by TLC and after completion (∼ 2 h), it was cooled to 0 °C and quenched carefully with methanol. Normal work up gave the product alcohol which after column chromatographic purification was analyzed by HPLC.
27. This is a very simplistic model based on the work of Corey (see ref. 2a) which explains the stereochemistry of the product. Refinement of our model by both experiment and computation are underway.