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首页> 外文期刊>Chemistry: A European journal >Kinetic Resolution of Aminoalkenes by Asymmetric Hydroamination: A Mechanistic Study
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Kinetic Resolution of Aminoalkenes by Asymmetric Hydroamination: A Mechanistic Study

机译：氨基烯类通过不对称加氢胺的动力学拆分：机理研究

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摘要

The kinetic resolution of chiral animoalkenes by hydroamination-cyclization was studied by using 3,3'-bis(triarylsilyl)-substituted binaphtholate rare-earth-metal complexes. The resolution of 1-arylaminopentenes proceeds with high efficiency and high tarns-diastereoselectivity, whereas the resolution process of 1-alkylaminopentenes suffers from decreasing resolution efficiency with increasing steric demand of the aliphatic substituent. Kinetic studies of the matching and mismatching substrate-catalyst pair by using enantiopure substrates and either the (R)- or (S)-binaphtholate catalysts revealed that the difference in resolution efficiency stems from a shift of the Curtin-Hammett pre-equilibrium. Although 1-arylaminopentenes favor the matching substrate-catalyst complex, preference for the mismatching substrate-catalyst complex for 1-alkylaminopentenes diminishes resolution efficiency. Nevertheless, the relative cyclization rate for the two diastereomeric substrate-catalyst complexes remains in a typical range of 7-10:1. Plausible attractive it interactions between the aryl substituent and either the metal center or the aromatic system of the bis(triarylsilyl)-substituted binaphtholate ligand may explain increased stability of the matching substrate-catalyst complex. Incidentally, the methoxymethyl (MOM)-substituted aminopentene 3g also exhibited a strong preference for the matching substrate-catalyst complex, possibly due to the chelating nature of the MOM substituent. The proximity of the stereocenter to the amino group in the aminoalkene substrate was crucial to achieve good kinetic resolution efficiency. The more remote P-phenyl substituent in 2-phenylpent-4-en-l-amine (5) resulted in diminished discrimination of the substrate enantiomers with respect to the relative rate of cyclization of the two substrate-catalyst complexes and a Curtin-Hammett pre-equilibrium close to unity.
机译：通过使用3,3'-双（三芳基甲硅烷基）-取代的邻萘二甲酸酯稀土金属配合物研究了手性苯胺通过加氢胺化环化反应的动力学拆分。 1-芳基氨基戊烯的拆分以高效率和高塔恩斯-非对映选择性进行，而1-烷基氨基戊烯的拆分过程随着脂肪族取代基的空间需求增加而降低了拆分效率。通过使用对映体纯底物和（R）-或（S）-联萘甲酸催化剂对匹配和错配的底物-催化剂对进行动力学研究，结果表明拆分效率的差异源于Curtin-Hammett预平衡的变化。尽管1-芳基氨基戊烯偏爱匹配的底物-催化剂配合物，但是偏爱于1-烷基氨基戊烯的错配底物-催化剂配合物降低了分离效率。然而，两种非对映异构底物-催化剂复合物的相对环化速率通常保持在7-10：1的范围内。芳基取代基与双（三芳基甲硅烷基）取代的邻萘二甲酸酯配体的金属中心或芳族系统之间可能存在的吸引人相互作用可能解释了匹配的底物-催化剂配合物的稳定性提高。顺便提及，可能由于MOM取代基的螯合性质，甲氧基甲基（MOM）取代的氨基戊烯3g也显示出对匹配的底物-催化剂配合物的强烈偏好。立体中心与氨基烯烃底物中的氨基的接近对于实现良好的动力学拆分效率至关重要。 2-苯基戊-4-烯-1-胺中较偏远的P-苯基取代基（5）导致底物对映体相对于两种底物-催化剂配合物和科廷-汉米特环化的相对速率的区别度降低平衡前接近统一。

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