Enantioselective photoreduction of arylalkyl ketones via restricting the reaction to chirally modified zeolite cages

Organic Letters

Volumn 2, Issue 7, 2000, Pages 937-940

  Shailaja, J ^a   Ponchot, Keith J ^a   Ramamurthy, V ^a  

^a Tulane University   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0001266633     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol000018e     Document Type: Article

References (23)

1. Joy, A.; Ramamurthy, V. Chem. Euro. J. In press.
2. Cohen, S. G.; Parola, A.; Parsons, G. H., Jr. Chem. Rev. 1973, 73, 141.
3. (a) Lewis, F. D.; Johnson, R. W.; Johnson, D. E. J. Am. Chem. Soc. 1974, 96, 6090.
4. (b) Stocker, J. H.; Kern, D. H. J. Chem. Soc., Chem. Commun. 1969, 204.
5. -5 mol) of 1 were added 26 mg of chiral inductor, 20 mL of hexanes, and 250 mg of activated NaY zeolite while stirring. The mixture was allowed to stir under nitrogen for 2-3 h and then irradiated for 3 h. The conversions in most experiments were in the range of 20 to 35% as monitored by GC. The zeolite was filtered, and the organic contents were extracted using acetonitrile. The chiral inductor was removed from the solution by column chromatography (silica gel/ hexanes-ethyl acetate). The solution was concentrated and analyzed on Supelco β-dex 350/1701 custom-made column. The enantiomeric excesses were measured both electronically and manually.
6. The chiral auxiliary approach has been employed to keep the reactant and the chiral inductor together within a cage, and this has yielded high de. (a) Joy, A.; Uppili, S.; Netherton, M. R.; Scheffer, J. R.; Ramamurthy, V. J. Am. Chem. Soc. 2000, 122, 728.
7. (a) Cohen, S. G.; Laufer, D. A.; Sherman, W. V. J. Am. Chem. Soc. 1964, 86, 3060.
8. (b) Pitts, J. N., Jr.; Letsinger, R. L.; Taylor, R. P.; Patterson, J. M.; Recktenwald, G.; Martin, R. B. J. Am. Chem. Soc. 1959, 81, 1068.
9. Seebach, D.; Daum, H.J. Am. Chem. Soc. 1971, 93, 2795.
10. Seebach, D.; Oei, H.-A.; Daum, H. Chem. Ber. 1977, 110, 2316.
11. (e) Homer, L.; Klaus, J. Liebigs. Ann. Chem. 1979, 1232.
12. Joy, A.; Scheffer, J. R.; Ramamurthy, V. Org. Lett. 2000, 2, 119.
13. The extent of ee depends on the water content of the zeolite. The ee will be in the range between 0 and 61% if the sample is not dried properly.
14. (a) Cohen, S. G.; Baumgarten, R. J. J. Am. Chem. Soc. 1965, 87, 2996.
15. (b) Cohen, S. G.; Chao, H. M.; J. Am. Chem. Soc. 1968, 90, 165.
16. Cohen, S. G.; Green, B. J. Am. Chem. Soc. 1969, 91, 6824.
17. Davidson, R. S.; Lambeth, P. F.; Younis, F. A.; Wilson, R. J. Chem. Soc., Chem. Commun. 1969, 2203.
18. (e) Parola, A. H.; Rose, A. W.; Cohen, S. G. J. Am. Chem. Soc. 1975, 97, 6202.
19. (f) Simon, J. D.; Peters, K. S. J. Am. Chem. Soc. 1981, 103, 6403.
20. (g) Manring, L. W.; Peters, K. S. J. Am. Chem. Soc. 1985, 107, 6452.
21. As pointed out by a referee, it is likely that the radical 5 is sufficiently long-lived for it to diffuse away from the cage in which it was generated. Such a process can result in a decreased ee.
22. Wagner, P. J.; Meador, M. A.; Giri, B. P.; Scaiano, J. C. J. Am. Chem. Soc. 1985, 107, 1087.
23. (b) Wagner, P. J.; Meador, M. A.; Park, B.-S. J. Am. Chem. Soc. 1990, 112, 5199.