High acceleration of the direct aldol reaction cocatalyzed by BINAM-prolinamides and benzoic acid in aqueous media
High acceleration of the direct aldol reaction cocatalyzed by BINAM-prolinamides and benzoic acid in aqueous media
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DOI：
10.1016/j.tetasy.2006.05.026
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发表时间：
2006-06-19
影响因子：
--
通讯作者：
Najera, Carmen
中科院分区：
文献类型：
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作者：
Guillena, Gabriela;del Carmen Hita, Maria;Najera, Carmen
由可回收的BINAM-脯氨酰胺衍生物有机催化的对映选择性直接羟醛缩合反应可以通过催化量的羧酸高度加速，而不会损害所获得的对映选择性。通过对合适的酸和反应条件的研究，苯甲酸在DMF水溶液或水溶液中得到最好的结果，具有高产率和对映选择性。因此，（S-a）-BINAM-L-Pro催化的对硝基苯甲醛和丙酮与苯甲酸的反应在-20 ℃下仅需8.5 h即可得到86%ee的预期产物。对于2-丁酮，异构体和反式异构体的比例为1：1，最高可达99%ee。对于环己酮，仅需2 h即可得到反式羟醛，最高可达99%dr和97%ee。在环戊酮的情况下，得到相反的非对映选择性，顺式异构体的ee最高可达65%，反式异构体的ee最高可达85%。(c)2006爱思唯尔有限公司保留所有权利。
The enantioselective direct aldol reaction, organocatalyzed by recoverable BINAM-prolinamide derivatives can be highly accelerated by a catalytic amount of a carboxylic acid without a detrimental of the obtained enantioselectivities. From the study of suitable acids and reaction conditions, benzoic acid in aqueous DMF or in water was shown to give the best results with high yields and enantioselectivities. Thus, the reaction between p-nitrobenzaldehyde and acetone catalyzed by (S-a)-BINAM-L-Pro and benzoic acid can be carried out at -20 degrees C in only 8.5 h to give the expected product with 86% ee. In the case of butan-2-one, the iso- and the anti-isomers are obtained in a 1:1 isomer ratio up to 99% ee. Cyclohexanone gives the anti-aldol in up to 99% dr and 97% ee in only 2 h. The opposite diastereoselectivity is obtained in the case of cyclopentanone with lower ee up to 65% for the syn and 85% for the anti-isomer. (c) 2006 Elsevier Ltd. All rights reserved.