Primary amine catalyzed direct asymmetric aldol reaction assisted by water
Primary amine catalyzed direct asymmetric aldol reaction assisted by water
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DOI：
10.1016/j.tetasy.2005.02.031
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发表时间：
2005-04-18
影响因子：
--
通讯作者：
Amedjkouh, M
中科院分区：
文献类型：
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作者：
Amedjkouh, M
在不对称直接羟醛缩合反应中，L-缬氨酸是一种活性催化剂。用20mol%的L-缬氨酸在35 ℃催化多种芳香醛与丙酮的羟醛缩合反应，得到中等至良好产率（48- 83%）和对映体过量（42-72%）的羟醛缩合产物。该反应在催化上更有效，在DMSO或DMF作为溶剂中，在相对于醛1摩尔当量的水存在下观察到最佳结果。考察了水浓度对反应速率和对映选择性的影响。因此，随着DMSO中水浓度的增加，对映选择性降低。而在苯丙氨酸存在下，反应活性和对映体选择性较低，生成的羟醛含量为25%，ee值为31%，而在苯甘氨酸存在下，羟醛生成量可忽略不计（< 5%）。我们的研究结果，提出了一种新的策略，在设计新的生物有机催化剂的直接不对称羟醛缩合反应。(c)2005爱思唯尔有限公司保留所有权利。
L-Valine was found to be an active catalyst in the asymmetric direct aldol reaction. The aldol reaction of a variety of aromatic aldehydes with acetone was catalyzed by 20 mol % Of L-valine at 35 degrees C with the aldol products obtained in moderate to good yields (48-83%,) and enantiomeric excesses (42-72%). The reaction was more efficient catalytically with best results observed in the presence of 1 mol equiv of water, with respect to the aldehyde, in either DMSO or DMF as solvent. The effect of water concentration on the reaction rate and enantioselectivity was also investigated. Thus, with increasing water concentration in DMSO there was decreasing enantioselectivity. However, the reaction in the presence Of L-phenylalanine showed a lower level of reactivity and enantioselectivity to afford the aldol in 25% with 31% ee. In marked contrast, reaction with L-phenylglycine resulted in the negligible formation of the aldol (< 5%). Our results, suggest a new strategy in the design of new bioorganic catalysts for direct asymmetric aldol reactions. (c) 2005 Elsevier Ltd. All rights reserved.