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首页> 外文期刊>Chemistry: A European journal >Asymmetric diethyl- and diphenylzinc additions to aldehydes by using a fluorine-containing chiral amino alcohol: A striking temperature effect on the enantioselectivity, a minimal amino alcohol loading, and an efficient recycling of the amino alcohol
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Asymmetric diethyl- and diphenylzinc additions to aldehydes by using a fluorine-containing chiral amino alcohol: A striking temperature effect on the enantioselectivity, a minimal amino alcohol loading, and an efficient recycling of the amino alcohol

机译：通过使用含氟手性氨基醇向醛中的不对称二乙基和二苯基锌加成：对对映选择性的显着温度影响，最小的氨基醇负载量和有效的氨基醇循环利用

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摘要

A chiral pyrrolidinylmethanol derivative containing perfluoro-ponytails (5) was prepared from (S)-proline. The use of this perfluoro-substituted amino alcohol in catalytic asymmetric additions of organozinc reagents to aldehydes affords products with high enantioselectivities in both pure hexane and a mixture of hexane and FC-72 (perfluorohexane). Enantiomeric excesses up to 94 and 88 % ee have been achieved in Et2Zn and Ph2Zn additions, respectively. For the reactions in the biphasic solvent system, a striking temperature effect was observed. Thus, when the temperature was raised from 0 to 40 degreesC the ee value of the product increased from 81 to 92 %. Furthermore, the catalyst loading could be remarkably low, and with only 0.1 mol % of amino alcohol 5 a product with 90 % ee was obtained in the Et2Zn addition to benzaldehyde in hexane. The perfluoro-ligand was easily recovered by simple phase separation, and until the ninth repetition its reuse proceeded without significant loss of enantioselectivity and reactivity.
机译：由（S）-脯氨酸制备含有全氟马尾辫的手性吡咯烷二甲醇衍生物（5）。在有机锌试剂向醛的催化不对称加成中使用这种全氟取代的氨基醇，可在纯己烷以及己烷和FC-72（全氟己烷）的混合物中提供具有高对映选择性的产物。在添加Et2Zn和Ph2Zn中，对映体过量ee分别达到94％和88％ee。对于双相溶剂体系中的反应，观察到惊人的温度效应。因此，当温度从0℃升高到40℃时，产物的ee值从81％增加到92％。此外，催化剂的负载可以显着降低，并且仅在氨基醇5中使用0.1 mol％的氨基苯甲醛中，在Et2Zn中除了苯甲醛以外，还获得了具有90％ee的产物。全氟配体很容易通过简单的相分离而回收，直到第九次重复，其再利用仍在继续进行而对映选择性和反应性没有明显损失。

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