DFT-B3LYP calculations were carried out to study the enantioselectivity of the （S）-4-hydroxylproline-catalyzed direct aldol reaction between acetone and 4-nitrobenzaldehyde. Four transition structures associated wit...DFT-B3LYP calculations were carried out to study the enantioselectivity of the （S）-4-hydroxylproline-catalyzed direct aldol reaction between acetone and 4-nitrobenzaldehyde. Four transition structures associated with the stereo-controlling step of the reaction have been determined. They are corresponding to the anti and syn arrangements of the methylene moiety related to the carboxylic acid group in enamine intermediate and the si and re attacks to the aldehyde carbonyl carbon. The effect of DMSO solvent on the stereo-controlling step was investigated with polarized continuum model （PCM）. The computed energies of the transition states reveal the moderate enantioselectivity of the reaction.展开更多
[Objective]The study aimed to screen the starch-degrading bacterium in bagasse and carry on the identification of strains s2g5-1 and s3g4-8.[Method]By using a variety of selective media,varieties of starch degrading b...[Objective]The study aimed to screen the starch-degrading bacterium in bagasse and carry on the identification of strains s2g5-1 and s3g4-8.[Method]By using a variety of selective media,varieties of starch degrading bacterium were isolated from the sugar cane bagasse form different stages of natural fermentation,then,primary screening and secondary screening were performed.[Result] Starch-degrading strains s2g5-1 and s3g4-8 were screened,and they were identified as Bacillus amyloliquefaciens according to their morphological,physiological,biochemical and molecular characteristics.[Conclusion]The research provided theoretical basis for factory application of bagasse.展开更多
文摘DFT-B3LYP calculations were carried out to study the enantioselectivity of the （S）-4-hydroxylproline-catalyzed direct aldol reaction between acetone and 4-nitrobenzaldehyde. Four transition structures associated with the stereo-controlling step of the reaction have been determined. They are corresponding to the anti and syn arrangements of the methylene moiety related to the carboxylic acid group in enamine intermediate and the si and re attacks to the aldehyde carbonyl carbon. The effect of DMSO solvent on the stereo-controlling step was investigated with polarized continuum model （PCM）. The computed energies of the transition states reveal the moderate enantioselectivity of the reaction.
基金Supported by the Central Public-interest Scientific Institution Basal Research Fund(2008hzs1J021,2009hzs1J033)~~
文摘[Objective]The study aimed to screen the starch-degrading bacterium in bagasse and carry on the identification of strains s2g5-1 and s3g4-8.[Method]By using a variety of selective media,varieties of starch degrading bacterium were isolated from the sugar cane bagasse form different stages of natural fermentation,then,primary screening and secondary screening were performed.[Result] Starch-degrading strains s2g5-1 and s3g4-8 were screened,and they were identified as Bacillus amyloliquefaciens according to their morphological,physiological,biochemical and molecular characteristics.[Conclusion]The research provided theoretical basis for factory application of bagasse.
