【作者】 李楠；

【导师】 龚军芳；

【作者基本信息】 郑州大学 ， 有机化学， 2021， 博士

【摘要】 钳形铱化合物是一类重要的钳形金属化合物,被用于催化多种类型的转化反应。特别是,结构多样化的非手性PCP钳形铱化合物在催化烷烃脱氢以及相关串联反应中表现出了高活性、高区域选择性以及高的热稳定性,是该类反应的“优势”催化剂,然而,PCP钳形铱催化剂也存在着一些局限性:在氮气氛围下或体系中有水分以及高浓度的烯烃时,催化活性会受到抑制;而双(噁唑啉)NCN钳形铱化合物在一定程度上可以克服这些局限性,比如在氮气、水以及烯烃的存在下很稳定,可以计量地用于烷烃、芳烃的活化以及烷烃脱氢反应中。尽管非手性的钳形铱化合物已经被广泛研究,但目前为止,关于手性钳形铱化合物的合成及催化应用的报道还非常有限。实际上,双(噁唑啉)苯配体是一类很好的手性配体骨架,可以通过商品化的、来源丰富的手性氨基醇制备,与双(噁唑啉)苯配体相比,双(咪唑啉)苯配体同样可以从手性氨基醇制备,但是,双(咪唑啉)苯配体的NR具有与O不同的电子和空间效应,而且,改变R基团也可以进一步调节配体的电子和空间效应,从而有利于筛选出高效的催化剂。在前期工作中,我们已经合成了双(咪唑啉)NCN钳形铂、钯、镍和铑化合物,并研究了它们在多种催化反应中的应用,此外,我们也合成得到了一些钳形铱化合物,并初步考察了其在不对称卡宾C-H键插入反应中的催化性能。在此基础上,本论文致力于合成双(咪唑啉)NCN钳形铱(Ⅲ)化合物,并对其在催化不对称卡宾C-H键和N-H键插入反应中的应用进行了比较系统地研究。第一章概述了钳形铱化合物的研究进展以及本课题组在双(咪唑啉)NCN钳形金属化合物的合成与催化应用方面的一些前期工作。基于此,提出了本论文的设计思路:合成双(咪唑啉)NCN钳形铱化合物,并将其应用于催化不对称卡宾插入反应。第二章分别利用手性氨基醇和手性二胺为手性源合成了 12个双(咪唑啉)苯钳形配体,接着钳形配体通过C-H键活化法与三水合三氯化铱反应制备了 12个双(咪唑啉)NCN钳形铱化合物。其中三个钳形铱化合物的结构通过单晶X-射线衍射进行了确证。第三章考察了 NCN钳形铱化合物在三类不对称C-H键插入反应中的催化性能。在α-芳基重氮乙酸酯与吲哚的反应中,加入NaBArF,催化剂的活性和产物的立体选择性明显提高,以最高86%的ee值得到了 33个C3取代的吲哚衍生物;在α-芳基重氮乙酸酯和1,4-环己二烯的反应中,通过在原有实验结果的基础上对α-芳基重氮乙酸酯进行进一步拓展,以最高99%的ee值得到了 8个C-H键插入产物;在3-重氮氧化吲哚和1,4-环己二烯的反应中,通过在原有实验结果的基础上对反应条件进一步优化以及底物拓展,以最高99%的ee值得到了 30个氧化吲哚衍生物。第四章探索了 NCN钳形铱化合物在α-芳基重氮乙酸酯和芳香伯胺的不对称N-H键插入反应。加入NaBArF后,催化剂的活性和产物的对映体选择性明显得到了提升,以最高92%的ee值得到了 42个α-氨基酸衍生物。该方法具有反应条件温和、官能团兼容性好、底物范围广等优点,且催化结果普遍优于该反应先前的文献报道。更多还原

【Abstract】 Pincer iridium complexes are a class of important pincer metal complexes,which can be used to catalyze various types of transformations.In particular,the structurally diverse achiral PCP-type Ir complexes exhibit high activity,regioselectivity and thermal stability in the catalytic dehydrogenation of alkane and the related tandem reactions,which are the dominant catalysts for such reactions.However,the PCP pincer Ir catalysts also have some limitations.The catalytic activity is often inhibited by N2,water and high concentrations of olefins.However,the NCN pincer Ir complexes with a bis(oxazolinyl)phenyl ligand can overcome these limitations to a certain extent.For example,they are stable in the presence of N2,water and olefins,and can be used for stoichiometric reactions of the activation of alkanes or aromatics and the dehydrogenation of alkanes.Although achiral pincer Ir complexes have been extensively studied,the reports on the synthesis and catalytic application of chiral one are still limited so far.In fact,bis(oxazolinyl)phenyl ligand is a kind of good chiral ligand skeleton,which can be achieved by using commercially available and abundant chiral amino alcohols.Compared with bis(oxazoline)ligand,bis(imidazoline)ligand can also be prepared from chiral amino alcohols.However,the group of NR in the bis(imidazoline)ligand has different electronic and steric effects from an oxazoline oxygen atom.Moreover,changing the R group can further tune the electronic and steric effects of the ligand,which is beneficial to the screening of efficient catalysts.In our previous work,we had synthesized chiral bis(imidazoline)NCN pincer platinum,palladium,nickel and rhodium complexes,and studied their applications in various catalytic reactions.In addition,we also synthesized some pincer iridium complexes,and preliminarily investigated their catalytic properties in asymmetric C-H bond insertion reactions.On this basis,the dissertation is dedicated to the synthesis of bis(imidazoline)NCN iridium(Ⅲ)complexes,and systematically studies on their application in the catalytic asymmetric C-H and N-H insertion reactions.In the first chapter,the research progress of pincer iridium complexes and some preliminary work of our group on the bis(imidazoline)NCN pincer metal complexes were summarized.Based on above research,the design idea of this dissertation was proposed.First,bis(imidazoline)NCN pincer iridium complexes were synthesized and then they were used as catalysts applied to asymmetric carbene insertion reactions.In the second chapter,12 bis(imidazolinyl)phenyl ligands were synthesized from chiral amino alcohols and chiral diamines,which could be converted to corresponding bis(imidazoline)NCN pincer iridium complexes after C-H bond activation with IrCl3·3H2O.Three of them were corroborated by single crystal X-ray diffraction.In the third chapter,the catalytic performance of NCN pincer iridium complexes on three types of asymmetric C-H insertion reactions were studied.In the reactions of α-aryl-α-diazoacetates with indoles,the catalytic activity and stereoselectivity were significantly improved with the addition of NaBArF,and 33 C3-substituted indole derivatives were obtained with up to 86%ee;in the reactions of α-aryl-α-diazoacetates with 1,4-cyclohexadiene,the substrate scope ofα-aryl-α-diazoacetate was further explored based on the original experimental results,and 8 C-H insertion products were obtained with up to 99%ee;in the reactions of 3-diazooxindoles with 1,4-cyclohexadiene,with the further optimized reaction conditions and the expansion of substrate scope,30 oxindole derivatives were obtained with up to 99%ee.In the fourth chapter,the N-H insertion reactions of aryl-α-diazoacetates with aromatic primary amines catalyzed by NCN pincer iridium complexes were investigated.With the addition of NaBArF,the catalytic activity and enantioselectivities of the products were obviously improved,and 42 α-amino acid derivatives were delivered with up to 92%ee.This method features mild reaction conditions,good functional group tolerance and wide substrate range.Moreover,the catalytic results are better than those reported in the previous literature.更多还原