Asymmetrically modified zeolite as a medium for enantioselective photoreactions: Reactions from spin forbidden excited states

Tetrahedron Letters

Volumn 38, Issue 51, 1997, Pages 8825-8828

  Abraham, Joy ^a   Robbins, Rebecca J ^a   Pitchumani, Kasi ^a   Ramamurthy, V ^a  

^a Tulane University   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

NORBORNENE DERIVATIVE;

ARTICLE; CHIRALITY; DRUG SYNTHESIS; ENANTIOMER; IN VITRO STUDY; PHOTOCHEMISTRY; REACTION ANALYSIS; STEREOCHEMISTRY; TECHNIQUE;

EID: 0343035544     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(97)10382-3     Document Type: Article

References (23)

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8. Gamlin, J. N.; Jones, R.; Leibovitch, M.; Patrick, B.; Scheffer, J. R.; Trotter, J. Acc. Chem. Res., 1996, 29, 203.
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10. (a) Breck, D. W. Zeolite Molecular Sieves: Structure, Chemistry and Use, John Wiley and Sons: New York, 1974.
11. (b) Dyer, A. An Introduction to Zeolite Molecular Sieves, John Wiley and Sons: New York, 1988.
12. (c) van Bekkum, H.; Flanigen, E. M.; Jansen, J. C. Introduction to Zeolite Science and Practice, Elsevier: Amsterdam, 1991.
13. (a) Leibovitch, M.; Olovsson, G.; Sundarababu, G.; Ramamurthy, V.; Scheffer, J. R.; Trotter, J. J. Am. Chem. Soc., 1996, 118, 1219.
14. (b) Sundarababu, G.; Leibovitch, M.; Corbin, D. R.; Scheffer, J. R.; Ramamurthy, V. J. Chem. Soc., Chem. Comm., 1996, 2159.
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19. -3 Torr). Benzonorbornadiene (5mg, 0.04mM) was introduced into this complex by stirring in hexane. The resulting complex was filtered, washed with hexane and irradiated (after degassing) as a slurry in hexane (4mL) for 2-3h (conversion ∼ 80%). The hexane portion was removed and the product was extracted with diethyl ether (15mL) and analyzed by HPLC (Column: Chiralcel OJ; Eluent: hexane; Analysis wavelength: 270 nm).
20. Ephedrine hydrochloride (160mg, 0.79 M) and the zeolite (2.4 g) were stirred in water (120 mL) for 18h at 65° C. After filtering, this complex was stirred again with ephedrine hydrochloride (160mg, 0.79 M) in water (120 mL) for 18h at 65° C. The chiral auxillary/zeolite complex (300 mg) was dried under vacuum (<3 mTorr) for 12h. The substrate benzonorbornadiene (5mg, 0.04M) was stirred with the dried chiral auxillary/zeolite complex in hexane (5mL) for 12h. The resulting complex was filtered and washed with minimum amount of hexane (∼2mL) and irradiated (after degassing) as a slurry in hexane (4mL) for 2-3h. The hexane portion was removed and the product was extracted with diethyl ether (15mL) and analyzed by HPLC.
21. (a) Li, X.; Ramamurthy, V. J. Am. Chem. Soc., 1996, 118, 10666.
22. (b) Robbins, R. J.; Ramamurthy, V. J. Chem. Soc. Chem. Comm., 1997, 1071.
23. Dry NaY/thionin (308 mg) was suspended in 9 mL of hexane. Chiral inductor (+)-Ψ-ephedrine hydrochloride (∼9 mg) was added and slurry was stirred at room temperature for one hour. 1-Methyl-4-phenyl-2-butene (0.1 mL) was added to stirring slurry. After an additional hour of stirring reaction mixture was placed in irradiation chamber, oxygen gas was bubbled through as irradiation took place. After four hours, the irradiation was stopped. Triphenylphospine was added with diethyl ether. The reaction mixture was allowed to stir for 1 hour to reduce and extract the oxidation products. Analysis was done by GC with a β-Dex chirasil column. The optimum separation condition was found to be an isotherm at 100° C. Assignments were made based on the behavior of the authentic alcohol. The retention times for the chiral 2° alcohols were 11.30 and 11.75 minutes.