Synthesis And Application Of Pyridylquinoxaline Derivatives

For decades, carbon– carbon bond formation is the main target of organic chemists. How to build carbon– carbon bond simply, effectively, cleanly, environment friendly is the major concern. Organic compounds could be simply classified by structure, chain compounds and ring compouds. In this artic- le, pyridylquinoxaline derivatives were designed and synthesized. These derivatives were applied to Suzuki– Miyaura reaction and cyclotrimerization reaction. Carbon– carbon bond was formed in a chain compound in the former reaction, and in a ring compound in the latter reaction.1. Design and synthesis of catalystsLigands with high steric hindrance were often used in Suzuki - Miyaura reaction. Because of toxic of phosphine compounds, N-coordinated ligands, pyridylquinoxaline derivatives, were designed and synthesized in this article. Coordinate properties was adjusted by introduce substituent to the pyridine ring, in order to study the influence of structure to the activity of catalysts.2. Suzuki– Miyaura reactionCorresponding palladium (II) complexes were obtained by the reaction of the ligands with PdCl2(CH3CN)2. These complexes were used as catalysts in Suzuki– Miyaura reaction. The best reaction condition was determined by filtering solvents and bases, and then extended to a series of substrates.3. Cyclotrimerization reaction of alkynesThe best reaction condition was determined by experiments. 1,3,5-triphenylbenzen was formed from phenylacetylene under this condition. The use of zinc iodideb changed the regioselectivity significantly, making 1,2,4-triphenylbenzen the main product. This reaction was easily manipulated and high regioselective. But can only be applied to limited substrates.