钌催化酮酯的氢化反应研究

发布时间：2018-04-25 07:01

本文选题：氢化 + α-酮酯　；参考：《陕西师范大学》2016年硕士论文

【摘要】：将酮和酯转变成相应的醇化合物是有机合成中的重要反应。传统的方法主要以化学计量的还原试剂,例如LiAlH4、NaBH4和BH3等对酮及酯进行还原,而该类还原试剂在使用过程具有潜在的危险性,例如毒性、后处理危险等。从原子经济和实用角度考虑,用氢气做为氢源,通过直接催化氢化酮及酯化合物的还原来获得醇类化合物是一个干净而又高效的方法。在过去的几十年里,由酮氢化还原为醇取得了很大进展,但是,将酯氢化为相应的醇仍然是一个很大的挑战,这主要归因于差的选择性及较低的催化活性。近年来,新型的催化体系被开发,在酯的还原反应中取得显著的成果,在这些催化体系中,大多基于铁、钴、钌、铱和锇为中心金属的螯合型络合物,在相对温和的条件下实现了对酯的氢化还原。其中最著名的例子为Ru-MACHO催化剂,实现了(R)-乳酸甲酯高效的氢化生成(R)-1,2-丙二醇的工业化生产。二醇化合物,如1,2-二醇和1,3-二醇,是一类重要的有机合成中间体,在活性药物成分的合成,有机官能团的转化,聚合物的合成等方面被广泛的应用。在文献报道的方法中,合成二醇化合物的方法主要有：烯烃的双羟基化反应及二硼烷基化,氢化还原羟基酯或二酮化合物,环氧化合物的开环,酶催化反应以及还原试剂还原酮酯等。在这些报道的方法中,直接氢化还原酮酯为二醇化合物提供了一种高效、原子经济的方法。本论文以Ru-MACHO螯合型催化剂为基础,开展了酮酯类底物的选择性氢化反应研究,通过考察反应的时间、温度、碱的类型、压力以及溶剂等各方面因素对氢化反应的影响。从而筛选出最优化的反应条件。其结果发现,该催化体系在催化α-酮酯的氢化反应中,可以高选择性的得到相应的1,2-二醇化合物或α-羟基酯化合物。进一步的研究表明,碱的类型及用量对酮酯的选择性氢化起着重要的作用。同时,该催化体系在α-酮酯的选择性氢化反应中具有很好的底物适应性,均获得比较理想的结果。α-酮酯的氢化反应的成功促使我们下一步开展β-酮酯的氢化反应研究,初步的研究结果表明,该催化氢化体系在温和的催化反应条件下能有效的选择性氢化酮羰基得到β-羟基酯,然而,在催化氢化合成1,3-二醇化合物的反应中,得到较多的副产物,进一步的研究正在进行当中。
[Abstract]:The conversion of ketones and esters to corresponding alcohols is an important reaction in organic synthesis. The traditional methods mainly use stoichiometric reduction reagents, such as LiAlH4, NaBH4 and BH3, to reduce ketones and esters. However, these reagents have potential risks in the process of use, such as toxicity, post-treatment risks and so on. From the point of view of atomic economy and application, it is a clean and efficient method to obtain alcohols by direct catalysis of ketones and esters by using hydrogen as a hydrogen source. In the past few decades, great progress has been made in the hydrogenation of ketones to alcohols. However, hydrogenation of esters to corresponding alcohols remains a major challenge, mainly due to poor selectivity and low catalytic activity. In recent years, novel catalytic systems have been developed, and remarkable results have been achieved in the reduction of esters, in which chelate complexes based on iron, cobalt, ruthenium, iridium and osmium are the central metals. The hydrogenation reduction of ester was realized under relatively mild conditions. One of the most famous examples is the Ru-MACHO catalyst, which has been used for the industrial production of the efficient hydrogenation of r-lactic acid methyl ester and the formation of r-1O2-propanediol. Diol compounds, such as 1o 2-diol and 1o 3-diol, are a kind of important organic synthesis intermediates. They are widely used in the synthesis of active drug constituents, the conversion of organic functional groups, the synthesis of polymers, and so on. Among the methods reported in the literature, the main methods of synthesis of diol compounds are: dihydroxylation of olefins and alkylation of diboron, hydrogenation of hydroxyl esters or diketones, ring opening of epoxy compounds, Enzymatic catalytic reaction and reductive reagent reducing ketone ester and so on. In these reported methods, direct hydrogenation of ketone esters provides a highly efficient, atomic economy method for diol compounds. Based on the Ru-MACHO chelating catalyst, the selective hydrogenation of ketone esters was studied. The effects of reaction time, temperature, alkali type, pressure and solvent on the hydrogenation reaction were investigated. The optimum reaction conditions were screened out. The results show that the catalytic system can produce the corresponding 1o 2-diol compound or 伪 -hydroxyl ester compound with high selectivity in the hydrogenation of 伪 -keto ester. Further studies show that the type and dosage of alkaloids play an important role in selective hydrogenation of ketone esters. At the same time, the catalyst system has good substrate adaptability in selective hydrogenation of 伪 -keto ester, and the satisfactory results are obtained. The success of hydrogenation of 伪 -keto ester leads us to further study on the hydrogenation of 尾 -keto ester. The preliminary results show that the catalytic hydrogenation system can effectively obtain 尾 -hydroxyl ester from ketone carbonyl group under mild catalytic reaction conditions. However, more by-products can be obtained in the catalytic hydrogenation of 1o 3-diol compounds. Further research is under way.
【学位授予单位】：陕西师范大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O621.251

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