L-proline/CoCl_2-catalyzed highly diastereo- and enantioselective direct aldol reactions

Karmakar A.; Maji T.; Wittmann S.; Reiser O.

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L-proline/CoCl_2-catalyzed highly diastereo- and enantioselective direct aldol reactions

机译：L-脯氨酸/ CoCl_2催化的高度非对映和对映选择性直接羟醛反应

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The CoCl_2/L-proline (1:2) system was found to be an excellent catalyst for direct aldol reactions. Excellent yields (up to 93 %) and a significant improvement in diastereoselectivity (anti/syn up to 45:1) as well as enantioselectivity (up to more than 99 % ee) compared with using proline as the sole catalyst were observed. This catalyst system was successfully applied to both cyclic and acyclic ketones in combination with aromatic and aliphatic aldehydes. In situ chelation of CoCl_2 and proline (1:2) is proposed to promote the reaction through a six-membered Zimmermann-Traxler type transition state involving the positioning of proline-enamine and the aldehyde through chelation to Co~(II).

机译：已发现CoCl_2 / L-脯氨酸（1：2）系统是直接进行羟醛反应的优良催化剂。与使用脯氨酸作为唯一催化剂相比，观察到极佳的收率（高达93％）和非对映选择性（高达45：1的反/合成）和对映选择性（高达99％ee以上）的显着提高。该催化剂体系已成功应用于环状和非环状酮与芳族和脂族醛的组合。提出原位螯合CoCl_2和脯氨酸（1：2）通过六元Zimmermann-Traxler型过渡态促进反应，该过程涉及脯氨酸-烯胺和醛通过与Co〜（II）的螯合定位。

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《Chemistry: A European journal》 |2011年第39期|共6页
作者
Karmakar A.; Maji T.; Wittmann S.; Reiser O.;
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正文语种 eng
中图分类应用化学;
关键词
aldehydes; aldol reaction; cobalt; diastereoselectivity; ketones;

机译：醛;醛醇缩合反应;钴;非对映选择性;酮;

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1. L-proline/CoCl_2-catalyzed highly diastereo- and enantioselective direct aldol reactions [J] . Karmakar A., Maji T., Wittmann S., Chemistry: A European journal . 2011,第39期

机译：L-脯氨酸/ CoCl_2催化的高度非对映和对映选择性直接羟醛反应
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L-proline/CoCl_2-catalyzed highly diastereo- and enantioselective direct aldol reactions

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