Qi Chuan-min, Yang Ling-chun, Sun Peng-li
Aug 26, 2010
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Journal
Chinese Journal of Chemistry
Abstract
Syntheses of 4 novel chiral azetidin-2-one derivatives, which were characterized by 1H NMR, ER, specific rotation and elemental analysis, through Staudinger cycloaddition reaction of Schiff base of benzaldehyde with chlorine substitution at different position in benzene ring, were described. For the first time, this type of 3S, 4R configuration azetidin-2-one mono-crystals with many chiral centers [(3S,4R)-3-hydroxy-N-[(S)-(1-phenyl)ethyl]-4-(2′-chlorophenyl)-azetidin-2-one mono-crystal] were obtained, the structures of which were determined by X-ray diffraction analysis. The effects of Schiff base of benzaldehyde with chlorine substitution at different position in benzene ring on stereoselectivity of Staudinger cycloaddition reaction products were discussed and the results are showed as below: 2-chlorophenyl Schiff base favored to yield 3S.4R configuration product, but 4-chlorophenyl Schiff base favored to yield 3S,4S configuration product. The reaction orientation of 2,4-dichlorophenyl Schiff base was determined by corporate effect of 2-and 4-chlorine, and that of the 4-chlorine was more obvious. In contrast to 4-chlorophenyl, although the main product was 3R, 4S configuration, 3-chlorophenyl owned lower selectivity.