节点文献
基于前、后修饰策略合成三氟甲基环戊二烯、富烯及芳硫醚的研究
Synthesis of Trifluoromethylated Cyclopentenedines, Fulvenes and Aryl Thiol Ethers Based on Pre-and Post-functionalization Strategy
【作者】 刘霄；
【作者基本信息】 东北师范大学 ， 有机化学， 2014， 博士
【摘要】 氟元素的丰度在地壳中居第十三位，主要以冰晶石（Na3AlF6）、荧石（CaF2）、氟磷灰石[Ca10(PO4)6F2]的形式存在。尽管自然界中氟元素含量可观，但由于氟盐（如冰晶石、荧石和氟磷灰石）在中性条件下的难溶性和弱亲核性等原因，限制了天然氟化物进入富水的生态系统，致使含有C F键的天然有机分子非常罕见。然而，有机分子中的含氟基团能够显著增强该分子的亲脂性、渗透性和抗氧化性，导致含氟有机化合物的稳定性和生物活性比不含氟的类似物更强，因此，20-30%的现代医药、农业化学品中至少含有一个氟原子。此外，其在生命科学、材料科学等领域也有重要的应用价值。近30年来，拓展含氟有机化合物的合成策略，尤其是三氟甲基化反应的研究备受关注，仅2013年，就有900余篇文献报道了各种含三氟甲基化合物的合成，应用多种三氟甲基化试剂，通过亲核、亲电、自由基等历程引入三氟甲基，构建结构多样的三氟甲基化合物。本论文利用已有深入研究的TMSCF（3三氟甲基三甲基硅烷，Ruppert–Prakash试剂）与二乙烯基酮及对醌化合物的1，2-亲核加成反应，制备了一系列三氟甲基二乙烯基醇及4-三氟甲基-对醌醇化合物，再通过高效、简洁的串联反应或“一锅法”反应合成多种新颖的碳环化合物，如多官能团化三氟甲基环戊二烯、富烯、芳硫醚化合物等。本论文所选原料如对醌具有可向其母环上引入取代基的特点（前修饰）；所用合成方法具有可在所构建的碳环化合物的环上引入取代基的特点（后修饰）。论文将结合实验结果对所作研究工作《基于前、后修饰策略合成三氟甲基环戊二烯、富烯及芳硫醚的研究》加以详细探讨。论文共分五章，第一章介绍了TMSCF3在三氟甲基化反应中的应用及三氟甲基化反应的最新研究进展；第二章阐述了本论文的选题依据。第三章介绍了多种不同类型的二乙烯基酮和对苯醌化合物的合成方法，及其与TMSCF3的1，2-加成反应。第四章介绍了一种新颖的“一锅法”反应。在温和条件下，三氟甲基二乙烯基醇可经由Nazarov反应生成单三氟甲基环戊二烯；或在Vilsmeier反应体系中一步得到单三氟甲基富烯衍生物。该反应无需过渡金属催化，是一种值得关注的高效的合成策略。第五章详细阐述了所发现的一种新合成策略。在温和的反应条件下，Lewis酸可催化对三氟甲基醌醇和二硫缩烯酮的反应，在醌醇的三氟甲基的邻和对位一步引入两个不同的官能团、随后芳构化，以较高产率、区域选择性地合成了用其他方法难以合成的三氟甲基芳基硫醚化合物。所创建的新合成方法具有可向所构筑芳环上强吸电子性的三氟甲基的邻位和对位同时引入两个不同的取代基团的特点。
【Abstract】 Fluorine is the13th most abundant element in the earth’s crust, where it occurspredominantly in the form of cryolite (Na3AlF6), fluorite (CaF2) and fluorapatite[Ca10(PO4)6F2]. In spite of this, there are only a very few nature organic molecules bearing aC F bond as most terrestrial F are bound in insoluble form and their poor nucleophilicityunder natural conditions, which hinders uptake by aqueous biological systems. However,fluorinated functional groups can remarkably enhance the lipophilicity, membranepermeability, elevate electronegativity and oxidation resistance of fluorine containing organiccompounds. Therefore, approximately20-30%of modern pharmaceuticals and agrochemicalscontain fluorine.In the recent30years, these advantages have stimulated an enormous amount of strategiesdirected to the synthesis of fluorinated compounds, especially the developments oftrifluoromethylation reactions as evidenced by over900publications in the year of2013.These references reported the introduction of trifluoromethyl group (CF3) into variousstructures by using diverse trifluoromethylated agents to construct trifluoromethylatedderivatives via nucleophilic, electrophilic and radical trifluoromethylations.Based on the extensively researched1,2-addition reaction of versatile reagent TMSCF3(trifluoromethyltrimethylsilane, Ruppert–Prakash reagent) with divinyl ketones or p-quinones,the study of this thesis fouses on the discovery of new strategies of the syntheses of severalnovel carboncycles including highly functionalized CF3-bearing cyclopentadiens, fulvenes,and aryl thiol-ethers by one-pot reactions and tandem reactions, respectively, starting from theeasily available3-CF3-1,4-dien-3-ols and4-CF3-p-quinol derivatives. We chose startingmaterials which could be introduced trifluoromethyl moiety into carbon fraworks such asp-quinones (“pre-functionalization” strategy) followed by introducing different functionalgroups regioselectively (“post-functionalization” strategy). This thesis combines experimentalresults and related reaction mechanisms to discuss the synthesis of trifluoromethylatedcyclopentenedines, fulvenes and aryl thiol ethers based on pre-and post-functionalizationstrategy in depth.The thesis is divided into five chapters. Reviewing the research on the use of TMSCF3and trifluoromethylation reactions in recent years is in the first chapter, and the thesisproposal is presented in chapter two.In chapter three, the preparation of the1,2-adducts of divinyl ketones, p-quinones basedon the1,2-addition reactions of TMSCF3is described.Chapter four describes a novel “one-pot” reaction to give CF3-bearing cyclopentadiens and fulvenes via Nazarov Reaction or under Vilsmeier conditions, respectively. Thismetal-free reaction is a noteworthy effective method.In Chapter five, a new strategy is discussed comprehensively. Themeta-double-functionalization/aromatization strategy based on the reaction of4-CF3-p-quinols and α-EWG ketene dithioacetals promoted by Lewis acid under mildcondition for the synthesis of functionalized trifluoromethylated aryl thiol ethers. Thisregiospecific manner has been developed that enables the introduction of two differentfunctional groups onto an “aromatic ring” in the ortho-and para-position to a strongelectron-withdrawing CF3group in a single step with high to excellent yields.