【作者】 刘旭；

【导师】 程旭； 李桂根；

【作者基本信息】 南京大学 ， 有机化学， 2020， 博士

【摘要】 绿色化学包含对于物质和能源两部分的要求,统一在化学反应这个过程中。随着国民经济的发展,国家对于绿色环保的化学化工生产技术的要求不断提高。绿色化学正是实现化学化工环保节能、可持续发展的研究领域,近年来成为国家绿色发展需求中的核心科学问题。因此,发展新型绿色化学合成方法成为有机合成研究的前沿热点。有机自由基化学的发展已经长达一个多世纪,由于其独特的结构特点使其在化学反应具有温和,高反应活性等特点。取代汉斯酯可以在多种条件下高效的产生自由基,无需高污染的试剂,在一系类绿色转化中获得广泛应用,本文基于取代汉斯酯开展相关研究。电作为清洁的二次能源,利用其独特的氧化还原特性在有机合成的理论以及应用研究方面有着重要的意义。近年来,随着人们对有机电化学反应机理的深入研究以及反应设备的改进,这种方法获得了广泛的应用,成为了有机合成的研究热点之一。本文基于取代汉斯酯的自由基化学及电化学两方面的研究启发,进而发展出交叉的研究工作。本论文的研究内容主要包括以下几部分:1、汉斯酯（腈）在自由基炔基化中的应用研究在温和条件下,我们第一次实现了C-4取代的汉斯酯或者汉斯腈应用于构建Csp-Csp³键的反应。通过使用K₂S₂O₈作为引发剂,C-4取代的汉斯酯裂解出烷基自由基进而与高价碘活化的炔反应。能够以高达97%的产率得到相应的炔化合物。另外,使用汉斯腈作为自由基给体,实现了含有季碳中心的炔化合物的构建。2、无外加化学还原剂条件下重水为氘源的电化学氘代反应研究我们开发出了一种不需要外加催化剂或者还原剂的条件下,使用重水作为氘源,制备α,β-不饱和羰基化合物的氘化反应。该反应操作简单,条件温和,所得产物氘代率高达99%,并且短时间内就可以反应完全。该反应阴极和阳极都使用石墨毡作为电极材料的,这是确保反应过程中中性条件下高化学选择性以及高氘代率的关键。与之前报道的使用化学计量的金属还原剂氘化反应相比,该方法具有条件温和,官能团耐受性广等优点。此外,通过机理研究表明,阳极析氧不仅避免了外部还原剂的使用,而且调节了反应混合物的p H值,使得反应液保持接近中性。3、多取代吡啶电化学还原反应研究采用牺牲阳极的方法,首次实现了多取代吡啶的脱酯重排合成全取代吡咯类化合物。反应使用比较廉价的锌为阳极,石墨毡为阴极,利用在电极下可以连续得电子的特点,顺利进行反应。该反应条件温和,底物兼容性较好。机理研究表明水作为氢源,溶剂不参与反应。更多还原

【Abstract】 Green Chemistry contains the requirements for material and energy,which are unified in the process of chemical reaction.With the development of the national economy,the requirements of green chemical production technology are increasing.Green chemistry is the research field to realize environmental protection,energy saving and sustainable development of chemical industry.In recent years,green chemistry has become the core scientific problem in the demand of national green development.Therefore,the development of new green chemical synthesis methods has become the forefront of organic synthesis research.The development of organic free radical chemistry has lasted for more than a century.Due to its unique structural characteristics,it has mild and high reactivity in chemical reactions.Substituted Hantzch esters can produce free radicals efficiently under various conditions without high pollution reagents,and are widely used in a series of green transformation.This paper is based on the research of substituted Hantzch esters.As a clean secondary energy,electricity has great significance in the theory and application of organic synthesis by its unique redox characteristics.In recent years,with the in-depth study of mechanochemical reaction mechanism and the improvement of reaction equipment,this method has been widely used and become one of the research hotspots in organic synthesis.In this paper,based on the research inspiration of free radical chemistry and electrochemistry of substituted Hantzch esters,cross research work has been developed.This thesis mainly includes the following parts:1.Application of Hantzsch Ester and Meyer Nitrile in Radical Alkynylation ReactionsWe report the first application of substituted Hantzsch ester and Meyer nitrile in the formation of Csp-Csp3 bonds.With K₂S₂O₈ as initiator,substituted dihydropyridine released an alkyl radical to react with BI-activated alkyne.The corresponding 1,2-disubsituted acetylene was obtained in up to 97%yield.By applying Meyer nitrile as an alkyl radical donor,intermolecular construction of a quaternary carbon center was fulfilled.2.Chemical-Reductant-Free Electrochemical Deuteration Reaction using Deuterium OxideWe report a protocol for electrochemical deuteration ofα,β-unsaturated carbonyl compounds under catalyst-and external reductant-free conditions with deuteration rates as high as 99%and yields up to 91%in 2 h.The use of graphite felt for both the cathode and the anode was key to ensuring chemoselectivity and high deuterium incorporation under neutral conditions without the need for an external reductant.This protocol has a number of advantages over previously reported deuteration reactions that use stoichiometric metallic reductants.Mechanistic experiments showed that O₂ evolution at the anode not only eliminated the need for an external reductant but also regulated the p H of the reaction mixture,keeping it approximately neutral.3.Electrochemical Reduction of Polysubstituted PyridineBy using sacrificial anode method,the deasterification and rearrangement of polysubstituted pyridines were realized for the first time to synthesize total substituted pyrrole compounds.The cheap zinc was used as anode and graphite felt as cathode.The reaction was carried out smoothly with the characteristics of continuous electron generation under the electrode.The reaction conditions were mild and the substrate compatibility was good.The mechanism study shows that water as the hydrogen source,solvent does not participate in the reaction.更多还原