导向基团辅助铑催化的惰性C-H键活化及官能化反应

发布时间：2018-02-24 00:26

本文关键词： 铑催化偶氮苯芳基硝酮 C H键活化交叉脱氢偶联反应　出处：《淮北师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：过渡金属催化的惰性C H键活化和官能化反应是当前的热门研究领域,已经发展成为构建C C键和C X键的有效方法之一。值得指出的是在这些反应体系中通过引入导向基可以成功实现反应区域选择性的绝对控制。虽然多种过渡金属催化剂都可以用于C H键活化反应,但是多数催化剂的活性不高,用量较大。反之,铑盐及其配合物作为催化剂因具有较好的稳定性和优秀的催化活性而被广泛用于有机催化反应。尤其在C H键活化的反应体系中更是表现出良好的官能团兼容性和选择性;同时,此类反应体系具有反应条件温和、操作简单和高效等优点。虽然过渡金属Rh催化的惰性C H键活化反应在提高反应的效率和选择性方面初有成效,但是催化的有机反应类型较少,仍需拓展反应的应用范围,进一步丰富惰性C H键活化反应的内容。本文以芳基偶氮苯、二芳基硝酮为反应底物,在导向基的辅助下采用高活性的铑配合物为催化剂对芳环上的C(sp2) H键进行选择性活化及官能化反应,具体研究内容如下:(1)以[Cp*RhCl_2]_2为催化剂,六氟锑酸银为添加剂,1,2-二氯乙烷(DCE)为反应溶剂,在110 o C件下反应20 h成功实现了芳基偶氮苯类化合物与乙酸烯丙酯的直接烷基化反应。在该反应体系中发现乙酸烯丙酯作为唯一的烷基化试剂,可以选择性的在偶氮基团的邻位进行烷基化,但是并没有分离得到传统的烯基化反应产物。该烷基化反应体系首次实现芳基偶氮的邻位烷基功能化反应,为非对称的偶氮化合物的合成提供了一个高效和原子经济性的合成方法。(2)采用交叉脱氢偶联策略,以[Cp*RhCl_2]_2为催化剂,Ag Sb F6为添加剂,一水合醋酸铜Cu(OAc)2?H2O为氧化剂,DCE为反应溶剂,可以顺利实现芳基偶氮苯和N-甲基吲哚、苯并VA唑及苯并噻吩的选择性交叉脱氢偶联反应,相应的偶联产物收率中等到良好。研究过程中发现该反应体系中仅有过渡金属Rh催化剂活性最高,同时这也是反应体系获得优秀区域选择性的关键。此方法为高度共轭芳烃类化合物的合成提供了新的合成方法。(3)实现了Rh(Ⅲ)催化N-a-二苯硝酮与VA唑啉酮类衍生物的直接C N键生成反应。初步发现在1,2-二氯乙烷为反应溶剂,六氟锑酸银、醋酸钠和冰醋酸为添加剂的反应体系中可以直接实现底物中芳环C(sp2) H键的活化和官能化反应,反应收率良好。另外,研究结果表明二芳基硝酮底物在发生胺化反应后,相应产物会快速直接释放出芳香醛。因此,该方法为邻氨基苯甲醛及其衍生物的合成提供了一个新的可选途径。
[Abstract]:Transition metal-catalyzed inert C-H bond activation and functionalization is a hot research field at present. It has been developed to be one of the effective methods to construct C C bond and C X bond. It is worth pointing out that the absolute control of region selectivity can be successfully achieved in these reaction systems by introducing the guide group, although there are many kinds of transition gold. All catalysts can be used in C-H bond activation reaction. However, the activity of most catalysts is not high and the amount of catalyst is large. Conversely, Rhodium salts and their complexes have been widely used in organic catalytic reactions because of their good stability and excellent catalytic activity. At the same time, this reaction system has the advantages of mild reaction conditions, simple operation and high efficiency, although the inert C-H bond activation reaction catalyzed by transition metal Rh has initial effectiveness in improving the efficiency and selectivity of the reaction. However, there are few types of catalytic organic reactions, so it is necessary to expand the scope of application of the reactions and further enrich the contents of the inert C-H bond activation reactions. In this paper, aryl azobenzene and diarylnitrone are used as the reaction substrates. The selective activation and functionalization of Cnsp2) -H bonds over aromatic rings were carried out using highly active rhodium complexes as catalysts assisted by the guidance group. The specific research contents are as follows: 1) [Cp*RhCl_2] 2 was used as catalyst. Silver antimonate hexafluoroantimonate was used as an additive, and DCE-2- dichloroethane was used as the reaction solvent. The direct alkylation of aryl azobenzene with allyl acetate was successfully realized in the reaction of 110 o C for 20 h. In this reaction system, allyl acetate was found to be the only alkylation reagent. The alkylation of aryl azo in the ortho position of azo group can be selectively carried out, but the products of traditional alkylation reaction are not separated. This alkylation reaction system is the first time to realize the o alkylation reaction of aryl azo. A highly efficient and atomic economical method for the synthesis of asymmetric azo compounds was provided. The cross dehydrogenation coupling strategy was adopted. [Cp*RhCl_2] 2 was used as catalyst Ag SB F 6 as additive, and copper acetate monohydrate was used as additive. The selective cross-dehydrogenation of aryl azobenzene with N-methylindoles, benzo-VA azole and benzothiophene can be successfully realized by using H _ 2O as oxidant and DCE as the solvent. The yield of the coupling product was medium to good. It was found that only the transition metal Rh catalyst had the highest activity in the reaction system. This method provides a new synthetic method for the synthesis of highly conjugated aromatic compounds, which provides a new method for the synthesis of highly conjugated aromatic compounds. The direct C-N bond formation reaction of the compound was carried out. It was preliminarily found that the reaction solvent was 2-dichloroethane, In the reaction system of silver hexafluoroantimonate, sodium acetate and acetic acid as additives, the activation and functionalization of the aromatic ring csp2) H bond in the substrate can be directly realized, and the yield of the reaction is good. The results show that the corresponding products can release aromatic aldehydes quickly and directly after the amination reaction of diaryl nitrone substrates. Therefore, this method provides a new alternative for the synthesis of o-aminobenzaldehyde and its derivatives.
【学位授予单位】：淮北师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O621.251

【相似文献】