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Volume 82, Issue 1
Received, 17th May, 2010, Accepted, 20th July, 2010, Published online, 21st July, 2010. |
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| Diastereoselective Cyclization Reactions of Chiral Proline Auxiliary-Substituted N-Benzoyl-α-dehydro(1-naphthyl)alaninamide Derivatives via Photoinduced Electron Transfer |
Yuhki Sato, Yuhta Haruyama, Tetsutaro Igarashi, and Tadamitsu Sakurai*
Material and Life Chemistry, Faculty of Engineering, Kanagawa University, 3-27-1 Rokkakubashi, Kanagawa-ku, Yokohama 221-8686, Japan |
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Abstract
Irradiation of the title 1-naphthylalaninamide derivatives [(Z)-1] bearing N’-substituted (S)-prolinamide auxiliaries in 1,2-dichloroethane and methanol containing triethylamine mainly afforded the corresponding (4S,5S)-4,5-dihydrooxazoles [(4S,5S)-2, diastereomeric excess (de) = 21–84%] and (4R,5R)-2 (de = 18–43%), respectively. Analysis of substituent and solvent effects on the diastereoselective photocyclization of (Z)-1 substantiated that steric bulkiness of the chiral auxiliary, solvent polarity, and intramolecular hydrogen bond are major factors controlling de, while intermolecular hydrogen-bonding and charge-transfer interactions invert the configuration of the dihydrooxazole diastereomer preferentially formed. |
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Graphical Abstract
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| Corresponding author; email: sakurt01@kanagawa-u.ac.jp |
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