Synthesis Of Heterocycles Containing Nitrogen Promoted By Silica-supported Catalysts

Heterocyclic chemistry is an important part of organic chemistry. About one third ofall the organic compounds are heterocyclic compound. The important branch ofheterocyclic compound is heterocyclic compounds containing nitrogen, which areextensively application in the intermediate of medicine, agrochemicals, dyestuffs and otherfield of chemicals.In this paper, we mainly studied on the synthesis of nitrogen containing heterocyclespromoted by silica-supported catalysts. It is divided into five chapters.In chapter1, we briefly introduced the application of silica-supported catalysts inorganic synthesis home and abroad.In chapter2, an efficient synthesis of2-(1H-pyrazolo[3,4-b]pyridin-6-yl)-3H-benzo[f]chromen-3-one derivatives were developed via the three-component dominoreaction of2-acetyl-3H-benzo[f]chromen-3-one derivatives with5-aminopyrazole andalcohols catalyzed by SSA under microwave irradiation conditions. The structures of allproducts were identified by their IR,1H NMR,13C NMR and HRMS analysis and some ofthem were further confirmed by X-ray diffraction analysis.In chapter3, a novel silica-supported I2catalyst was prepared and evaluated for theapplication in the synthesis of quinoxaline derivatives under solvent-free conditions at thefirst time. It was found that this catalyst was efficient in the synthesis of quinoxalines. Theremarkable features of this green, new methodology are high conversions, cleaner reactionprofile, simple experimental and work-up procedures. And the reaction mechanism wasproposed.In chapter4, a convenient approach to the synthesis of2-phenyl-1H-benzo[d]imidazole derivatives was developed via the reaction of o-phenylendiamine derivatives andaldehydes catalyzed by SSA under solvent-free conditions. By controlling the conditions ofreactants and mole ratio of reactants, benzimidazole derivatives and N-substitutedbenzimidazole derivatives can be obtained, respectively. In chapter5, a simple and efficient synthesis of pyrrolo[2,3,4-kl]acridine-1-onederivatives via the cascade reaction of isatins and enaminones catalyzed by silica sulfuricacid (SSA) has been established. This method has the advantages of a highly catalyticnature, easy to handle procedure, short reaction time, recycle exploitation, insensitivity toair and moisture and excellent to good yields. The catalyst could be recycled at least fivetimes.The advantages of the above mentioned reactions are readily accessible startingmaterials, mild reaction condition, short reaction time, simple operation, environmentalfriendliness and good yields.