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首页> 外文期刊>Chemistry: A European journal >Ruthenium-catalyzed asymmetric hydrogenation of 3-oxoglutaric acid derivatives: A study of unconventional solvent and substituent effects
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Ruthenium-catalyzed asymmetric hydrogenation of 3-oxoglutaric acid derivatives: A study of unconventional solvent and substituent effects

机译：钌催化的3-氧戊二酸衍生物的不对称氢化：非常规溶剂和取代基效应的研究

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摘要

A series of 3-oxoglutaric acid derivatives have been hydrogenated in different solvents in the presence of [RuCl(benzene)(S)-SunPhos]Cl (SunPhos=(2,2,2′,2′-tetramethyl-[4,4′-bibenzo[d][1,3]dioxole] -5,5′-diyl)bis(diphenylphosphine)). Unlike simple β-keto acid derivatives, these advanced analogues can be readily hydrogenated in uncommon solvents such as THF, CH_2Cl_2, acetone, and dioxane with high enantioselectivities. Two possible catalytic cycles have been proposed to explain the different reactivities of these 1,3,5-tricarbonyl substrates in the tested solvents. The C-2 and C-4 substituents had notable but irregular influence on the reactivity and enantioselectivity of the reactions. More pronounced solvent effects were observed: the ee values increased from around 20 % in EtOH or THF to 90 % in acetone. Inversion of the product configuration was observed when the solvent was changed from EtOH to THF or acetone, and a mixed solvent system can lead to better enantioselectivity than a single solvent. Pronounced solvent effects: 3-Oxoglutaric acid derivatives have been hydrogenated in various solvents with high enantioselectivities (see scheme). Inversions of the product configuration were observed when the solvent was changed. Mixed solvent systems can give better enantioselectivities than a single solvent.
机译：[RuCl（苯）（S）-SunPhos] Cl（SunPhos =（2,2,2'，2'-四甲基-[4,4] ′-联苯并[d] [1，3]二恶唑] -5，5′-二基）双（二苯基膦））。与简单的β-酮酸衍生物不同，这些先进的类似物可以在对映选择性高的不常见溶剂（如THF，CH_2Cl_2，丙酮和二恶烷）中容易氢化。已经提出了两个可能的催化循环来解释这些1,3,5-三羰基底物在测试溶剂中的不同反应性。 C-2和C-4取代基对反应的反应性和对映选择性具有显着但不规则的影响。观察到更明显的溶剂效应：ee值从EtOH或THF中的约20％增加到丙酮中的90％。当溶剂从EtOH变为THF或丙酮时，观察到产物构型的转化，并且混合溶剂体系比单一溶剂可导致更好的对映选择性。明显的溶剂作用：3-氧戊二酸衍生物已在具有高对映选择性的各种溶剂中氢化（参见方案）。当更换溶剂时，观察到产物构型的转化。混合溶剂体系比单一溶剂具有更好的对映选择性。

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