Study Of Transition-metal-catalyzed 2-arylpyridines Ortho C-H Bond Activation Reactions

My research was focused on three sections as follows:1. Rhodium-catalysed cross-coupling reaction of 2-phenyl pyridine derivatives with 1,3-azole compoundsBiaryls are an important class of organic compounds in nature, which is the basic skeleton of a variety of natural products and advanced materials, especially antibiotics, anticancer, antifungal and anti-hypertensive agents and other compounds all contain biaryl structure. The construction of new C-C bond by transition metal catalyzed double C-H activation is a hot topic in organic synthesis research. Based on dehydrogenation cross-coupling (CDC) research strategies, we firstly proposed dual activating C-H bond of 2-phenyl pyridine and benzothiazole by using rhodium acetate as catalyst, copper acetate as oxidizing agent, cuprous iodide as additive to obtain biaryl compounds by oxidative coupling. The method showed the characteristics of environmentally friendly, the good regioselectivity, and atomic economy.2. Copper participation directed C-H bond ortho-functionalization of 2-phenyl pyridine halogenation reactionsHalogenated aromatic compounds are an important part of many kinds of bioactive molecules and pharmaceutical agents, and they are also an important precursor of many classic reactions. Because organic halides have great potential application value, the research on the development of a new synthetic strategy is very meaningful, and it also remains a critical challenge in organic chemistry. This part was designed to activate ortho C-H bond of 2-phenyl pyridine by employing copper acetate as copper salt and NCS as chlorine source to obtain double chlorinated aromatic compounds. This method was easy to obtain cheap raw materials, functional group compatibility, environmentally friendly.3. Study on synthesis technics of Polyethylene glycol monomethyl ether methacrylateThe polycarboxylate superplasticizer is the most efficient water reducing agent; the synthesis of superplasticizer is a hot topic. Polyethylene glycol monomethyl ether methacrylate is an important macromonomer for synthesis of polycarboxylate superplasticizer. The chapter was mainly focused on different molecular weight methoxypolyethylene glycols (MPEG-1200 and MPEG-5000 to synthesis polyethylene glycol monomethyl ether methacrylate.Taking methacrylic acid (MAA) and methoxy polyethylene glycol (MPEG-1200) as the raw materials, the synthetic of the methoxy polyethylene glycol methacrylate ester (MPEGMA) was prepared with the direct esterification method. Through screening and optimization, we obtained the optimum esterification conditions:n(MPEG):n(MMA)=1.3, the amount of p-toluenesulfonic acid catalyst was 1%(the total quality of reaction as a benchmark, the same below), the amount of quinol inhibitor was 0.2%, the reaction time was 12 h under 110 ℃, and the esterification rate could achieve 95%.Taking methacrylic anhydride (HMMA) and methoxy polyethylene glycol (MPEG-5000) as the raw materials, the synthetic of the methoxy polyethylene glycol methacrylate ester (MPEGMA) is prepared with the direct esterification method. Through the experiments, the optimum conditions were:n(HMMA)/n(MPEG)=4, the amount of 4-N,N-dimethyl-pyridine catalyst was 20%(With respect to the molar amount of methacrylic anhydride, the same below), the amount of quinol inhibitor was 0.2%, the amount of 1,2-dichloroethane solvent was 10 volume, reaction time was 18 h under the reflux and N2 protection, the esterification rate reaches 97%. The result showed that using the method of esterification of methacrylic anhydride and MPEG-5000 was a good method for the synthesis of polyethylene glycol monomethyl ether methacrylate.