Study Of Rhodium Catalyzed The Reaction Of 2-aryl Pyridines With Terminal Alkynes

My research was focuses on three sections as follows:1. Study of Rhodium Catalyzed The Reaction of 2-Aryl pyridines with Terminal AlkynesPyr ido [2, 1-a]iso indoles are very important structural motifs, which are widely applicated in pharmaceuticals, dyes and functional materials. Although pyrido [2,1-a] iso indoles have so extensive application, there are few literatures about the synthesis of these compounds. The preactivated substrates are usually used to synthesis compounds of this type via free radical cyclization in traditional methods. We firstly put forward a synthesis method of rhodium catalyzed direct oxidative C-H acylation of 2-aryl pyridines with terminal alkynes to generate pyrido[2,1-a]isoindoles. This method is green and efficient, well tolerant of different functional groups, with good regioselectivity and in accordance with atom economy.2. Study on Reaction Mechanism of Rhodium Catalyzed Reaction between 2-Aryl pyridines and Terminal AlkynesWe developed a method to obtain pyrido [2,1-a] iso indoles through oxidative coupling between 2-aryl pyridines and terminal alkynes in 140℃ under air atmosphere by using rhodium acetate as catalyst, copper acetate as oxidant, cuprous iodide as additive, the mixture of N, N-dimethylacetamide and o-xylene as solvent. We captured the Rh (Ⅲ) complex of this reaction process, which was an important reaction intermediate and was characterized by X-Ray structural analysis and NMR. Meanwhile, we exploited an efficient method to generate this complex. In addition, we proved that Rh (Ⅲ) complex was the real catalyst, Cu (Ⅱ) was the oxidant of Rh (Ⅰ) to Rh (Ⅲ), Cu (Ⅰ) played an important role in enhancing the yield of products, the oxygen atom came from the oxygen in air. Eventually we proposed a plausible mechanism of this reaction according to the literature and our reaction study.3. Transition Metal-Free Catalyzed C-3 Formylation of IndolesIndoles are important backbones of functional compounds. They are widely presented in a large number of biologically active natural products, which are closely related to life activities. 3-formylindoles are key intermediates for the preparation of bioactive molecures and indole alkaloids. The C-3 formylation of indoles are attracted profoundly by the majority of organic chemistry research personnels based on the extensive application of these compounds and the particular chemical activity of indole rings. We developed a synthesis method of transition metal-free catalyst direct C-3 formylation of indoles with hexamethylenetetramine by using potassium persulfate as oxidant in combination with literature reports and continuous exploration. This method is efficient and economic, environment-friendly and in mild conditions.