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首页> 外文期刊>Chemistry: A European journal >Asymmetric Hydrogenations One by One:Differentiation of up to Three beta-Ketocarboxylic Acid Derivatives Based on Ruthenium(II)-Binap Catalysis
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Asymmetric Hydrogenations One by One:Differentiation of up to Three beta-Ketocarboxylic Acid Derivatives Based on Ruthenium(II)-Binap Catalysis

机译：一对一不对称加氢：基于钌（II）-Binap催化的多达三种β-酮基羧酸衍生物的区分

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摘要

Noyori-type reductions of pairs of beta-ketoamides and beta-ketoesters with elemental hydrogen(4 bar)proceeded substrate by substrate.When Et2NH~(2+)[{RuCl(S)-binap}2](mu-Cl)_3~-was employed as a catalyst in a methanol or ethanol solution,the substrates were reduced at room temperature in the order beta-ketopyrrolidide > beta-ketopiper-idide >= beta-keto(N,N-diethylamide)> beta-keto(alkyl esters)> beta-keto(oligo-fluoroalkyl esters).This is the first time that P-ketoamides have been reduced asymmetrically(91 to > 98 % ee)under such mild conditions.Monitoring the concentrations of these beta-ketocarboxyl acid derivatives and their respective hydrogenation products over the course of time showed that the most electron-rich substrate is captured by the catalyst preferentially and exo-thermically;whether this occurs rever-sibly or irreversibly remains to be determined.The hydrogenation product is subsequently formed.The last transformation includes the rate-determining step.The combination of these events explains why starting from appropriate mixtures of substrates a "first-choice substrate" reacted from early on while the "second-choice substrate" stayed virtually untouched over an extended period of time and reacted no earlier than after the "first-choice substrate" had disappeared.From then onward,however,the "second-choice substrate" also reacted relatively rapidly.
机译：当Et2NH〜（2 +）[{RuCl（S）-binap} 2]（mu-Cl）_3时，通过元素氢（4 bar）对β-酮酰胺和β-酮酸酯对进行Noyori型还原。 -在甲醇或乙醇溶液中用作催化剂，在室温下将底物按以下顺序还原：β-酮吡咯烷酮>β-酮戊二酸酯> =β-酮（N，N-二乙酰胺）>β-酮（烷基酯）>β-酮（低聚氟代烷基酯）。这是在这种温和条件下首次将P-酮酰胺不对称还原（91至> 98％ee）。监测这些β-酮羧酸衍生物的浓度以及它们各自的氢化产物随时间的推移表明，最富电子的底物被催化剂优先地和放热地捕获;是否可逆或不可逆地发生是有待确定的，随后形成了氢化产物。最后的转换包括速率确定步骤。这些事件解释了为什么从合适的底物混合物开始，“首选底物”从早期开始反应，而“第二选择底物”在较长时间内几乎保持不变，并且反应不早于“第一选择底物”从此以后，“第二选择基质”的反应也相对较快。

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