【作者】 汤日元；

【导师】 向建南； 李金恒；

【作者基本信息】 湖南大学 ， 有机化学， 2014， 博士

【摘要】 C-H官能化反应是一种通过断裂C-H键,直接导入各种官能团,构建C-C键和C-杂原子键的技术方法。C-H键官能化反应避免使用预先官能团化的反应物,直接实现化合物的官能化,大大提高原子经济利用效率,减少废物的排放。应用C-H官能化反应技术,构建药物先导骨架,或对药物先导化合物直接官能团化,合成多样性的活性化合物,对于药物分子的高通量筛选具有重要意义。C-S键,吲哚以及吡唑骨架广泛存在于天然产物和药物分子之中。应用简单、快捷、高效的技术方法构建这些骨架具有重要的现实意义。而C-H官能化技术则可以为硫醚,吲哚以及吡唑等衍生物的合成提供最为简便的方法,通过导入各种各样的官能团,合成多样性的活性分子,为相关药物分子的设计与合成打下坚实的基础。本论文主要研究C-H氧化反应技术在合成硫醚,吲哚以及吡唑衍生物中的应用,本文内容包括以下四个部分：1.综述了近10年来基于氧化脱氢偶联反应和过渡金属催化的氮原子邻位sp3C-H键官能化反应进展。基于氧化脱氢偶联反应的氮原子邻位sp3C-H键官能化反应研究领域,归纳成三部分分别叙述：(1)无金属参与的氮原子邻位sp3C-H键官能化研究进展；(2)金属参与的氮原子邻位sp3C-H键官能化研究进展；以及(3)光催化的氮原子邻位sp3C-H键官能化研究进展。在过渡金属催化的氮原子邻位sp3C-H键官能化研究领域,根据反应类型分成三部分进行叙述：(1)氮原子邻位sp3C-H键氢氨基烷基化反应；(2)氮原子邻位sp3C-H键芳基化反应；以及(3)其它个别反应。2.发现了一种无金属参与的分子筛促进TBHP氧化酰胺氮原子邻位或醚的氧原子邻位sp3C-H键的硫化反应,合成S,N-杂化合物和S,O-杂化合物的技术方法。在4A分子筛和TBHP的共同作用下,通过氧化脱氢途径,将氮原子或氧原子邻位的sp3C-H键氧化脱氢生成自由基,然后被二硫醚中的S-S键捕获,发生硫化反应形成C-S键。该硫化反应方法适用范围广,参与反应的酰胺可以是N,N-二甲基甲酰胺、N,N-二甲基乙酰胺和N-甲基吡咯烷酮；氧醚可以是四氢呋哺、吡喃、叔丁基甲醚和乙二基二甲醚；二硫醚可以是各种基团取代的二芳基二硫醚和二苄基二硫醚。在4A分子筛和TBHP的氧化体系中,这些底物反应高效,能得到中等或优良的产率。有意义的是,应用TBHP氧化的硫化反应方法,可以使邻氨基苯二硫醚与N,N-二甲基乙酰胺先发生硫化反应,然后再进一步氧化环化,合成系列苯并噻哗衍生物。更为重要的是,氟虫腈前体吡唑基二硫醚(4,4’-二硫二基双(5-氨基-1-(2,6-二氯-4-三氟甲基苯基-1氢-吡唑-3-甲腈)也能顺利地分别与N,N-二甲基乙酰胺和四氢呋喃反应,得到相应的氟虫腈类似物。杀虫活性测试表明,这两种氟虫腈类似物对粘虫和苜蓿虫具有优良的杀虫活性。3.探索了一种钯催化α-氨基羰基化合物的C-N键选择性氧化断裂,与吲哚发生氧化脱氢偶联反应合成3-氧代羰基吲哚衍生物的方法。在Pd(OAc)2, Cu(OAc)2和HOAc的催化体系中,一系列含取代基的吲哚能与各种a-氨基羰基化合物顺利地发生氧化脱氢偶联反应,合成多样性的3-氧代羰基吲哚衍生物。更有意义的是,2-苯乙炔基苯胺作为吲哚的前体能与α-氨基羰基化合物反应,一锅法合成2-取代的3-氧代羰基吲哚衍生物。首先,将2-苯乙炔基苯胺在PdCl2的催化下,发生亲电环化反应,合成2-取代吲哚衍生物,然后再加入a-氨基羰基化合物,Cu(OAc)2和HOAc,继续反应有效地合成相应的吲哚衍生物。HRMS机理研究表明,α-氨基羰基化合物先被氧化,生成亚胺阳离子过渡态,然后与吲哚氧化偶联,然后再次生成亚胺阳离子过渡态,发生水解氧化,脱去苯胺得到3-氧代羰基吲哚衍生物,同位素实验证明羰基中的氧原子来源于水。值得指出的是,在对甲苯磺酸的催化下,3-氧代羰基吲哚的双羰基能与两分子吲哚发生环化反应,构建稠氮杂环化合物。得到的稠氮杂环化合物具有优良的荧光性能,能有效地检测Hg2+和Fe3+。4.建立了一种由Ni(II)催化氧化三分子α-氨基羰基化合物环三聚反应,合成多取代吡唑衍生物的方法。在空气氛围下,(C5H5)Ni(II)Cl(PPh3)/PhCO2H体系能有效地催化α-氨基羰基化合物发生环三聚串联反应,合成多样性的多取代吡唑衍生物,产率高达75%。利用ESI-HRMS实时在线分析以及控制实验,探究了反应中生成的中间体,得出了原料,中间体和产物的变化曲线,描绘了α-氨基羰基化合物环三聚的反应机理。反应机理表明吡唑环的构建经历了氧化脱氢,脱胺,重建两个C-C键,一个N-N键,以及羰基的异构化脱羟基等过程。更多还原

【Abstract】 The C-H functionalization is a reaction that cleaves a carbon-hydrogen bond for direct introduction of various functional groups into the carbon atom for the formation of the carbon-carbon bonds and carbon-heteroatom bonds. The C-H functionalization can avoid the use of pre-functionalized substrate, remarkably improve the atom-economic efficiency and reduce the discharge of waste material. The C-H functionalization method has been widely applied to construct some lead skeleton of drugs and diverse bioactive compounds, thereby making it significant in the high throughput drug screening.The carbon-sulfur bond, indole and pyrazole motifs are embedded in numerous natural products and pharmaceuticals. For these reasons, many elegant methods have been delevoped for their construction. In this field, the C-H functionalization serves as one of the most important and efficient methods for direct introduction of functional groups to form diverse thioether, indole and pyrazole derivatives, which can pave the way for the design and synthesis of corresponding pharmaceuticals, as well as for organizing the bioactive molecular libraries.This dissertation focuses on the synthesis of thioethers, indoles and pyrazoles through the C-H bond oxidation strategy. The content of dissertation includes four parts:1. Recent advances in the functionalization of sp3C-H bond adjacent to a nitrogen atom via the metal-free oxidative dehydrogenation coupling reaction or transition metal-catalyzed process. The functionalization of sp3C-H bond adjacent to a nitrogen atom through oxidative dehydrogenation coupling reactions include three ways:(1) metal-free mediated sp3C-H bond functionalization,(2) metal-catalyzed sp3C-H bond functionalization, and (3) photoredox catalyzed sp3C-H bond functionalization. According to the type of reaction, the research field of transition metal-catalyzed functionalization of sp3C-H bond adjacent to a nitrogen atom was also discussed involving three parts:(1) hydroaminoalkylation of sp3C-H bond adjacent to a nitrogen atom,(2) arylation of sp3C-H bond adjacent to a nitrogen atom, and (3) some other reactions.2. A new method for metal-free molecular sieve-promoted TBHP-mediated oxidative thiolation of sp3C-H bond adjacent to a nitrogen atom in amides or to an oxygen atom in ethers has been developed for the synthesis of S,N-heterocyclic compounds and S,O-heterocyclic compounds. In the presence of4A molecular sieve and TBHP, the oxidative deprotonation of a sp3C-H bond adjacent to a nitrogen atom or an oxygen atom was achieved to produce a carbon radical. It could be trapped by the S-S bond of disulfide to form the C-S bond. The present thiolation method is general for a wide range of substrates, including amides (DMF, DMAc and1-methylpyrrolidin-2-one), ethers (tetrahydrofuran, tetrahydro-2H-pyran,2-methoxy-2-methylpropane and1,2-dimethoxyethane) and disulfides (diaryl disulfides and dibenzyl disulfide). Significantly, this tiolation method could be applied to the synthesis of benzothiozoles derivatives from2,2’-disulfanediyldianiline and amides through the thiolation and oxidative cyclization cascade process. Moveover, the present thiolation method was viable for the synthesis of pesticide fipronil analogues by the reaction of pyrazole disulfide with DMAc or THF, respectively. Indoor pesticidal activities test indicated that the two fipronil analogues have highly pesticidal activities for the mythima sepatare and aphis medicaginis.3. A new and selective C-N bond oxidative cleavage method to3-acylated indoles by Pd-catalyzed oxidative cross coupling of indoles with a-amino carbonyl compounds has been established. In the presence of Pd(OAc)2, Cu(OAc)2and HOAc, a wide range of substituted indoles successfully reacted with a-amino carbonyl compounds to form diverse3-oxoacetylindole derivatives. Importantly, the oxidative coupling method allows one-pot reaction of2-ethynylanilines with a-amino carbonyl compounds to afford the2-substituted-3-oxeacetylindoles.2-Ethynylanilines was firstly underwent an electrophilic cyclization catalyzed by PdCl2, affording a2-substituted indole, followed by reaction with a-amino carbonyl compounds, Cu(OAc)2and HOAc to yield the corresponding indole derivatives. Mechanism research on HRMS indicated that a-amino carbonyl compound was firstly oxidated to an imine cation intermediate, followed by coupling with indole in the presence of palladium catalysis. The in-situ formed intermediate was further oxidated to an imine cation, followed by hydrolysis, oxidation and deamination afforded the3-oxoacetylindoles. The isotope experiments demonstrated that the oxygen atom in carbonyl derived from water. It is noteworthy that in the presence of4-methylbenzenesulfonic acid the cyclization of indolyl diones with indole can be achieved to access polyheterocyclic compounds with good fluorescent properties, which can be employed as efficient probes for Hg2+and Fe3+ions.4. A new strategy for the synthesis of multi-substituted pyrazoles is presented by Ni-catalyzed oxidative cyclotrimerization of a-amino ketones. In the presence of (C5H5)Ni(II)Cl(PPh3), PhCO2H and air, a series of a-amino ketones smoothly underwent the oxidative cyclotrimerization to afford various multi-substituted pyrazoles (up to75%yield). The ESI-HRMS real-time analysis and control experiments were used to investigate the reaction intermediates and materials balance. A change curve chart for starting material, intermediates and products was given, and a possible reaction mechanism was discussed. The reaction mechanism displays that this unprecedented method allows three a-amino ketones to undergo sequential multiple deprotonations and deamination through two C-C bonds, one N-N bond formation, carbonyl isomerization and dehydration cascade.更多还原