Research On Copper Nanoparticles Catalyzed Synthesis Of Nitrogen-oxygen-containing Heterocylic Compounds

Nitrogen, oxygen heterocyclics are common structural units of natural products and exhibitinteresting and unique physiological and pharmaceuticals activities. The research on the syntheticmethodology of them is of great interest, and various synthetic methods were reported. However,most of them suffered some disadvantages, such as harsh reaction conditions, environmental hazards,and others. Recently, based on the concept of green chemistry, seeking more wild methods toconstruct the nitrogen-and oxygen-containing heterocyclics has become a hot issue in the currentresearch.In this thesis10-20nm diameter copper nanoparticles were prepared by using liquid-phasereduction, and were characterized by TEM and XRD analysis. The copper nanoparticles were thenutlized as catalysts in the construction of2-substituted benzoxazoles and3-substituted isocoumarinswith or without the promotion of ligands. The specific content are as fellows:（1） Copper nanoparticles catalyzed synthesis of2-substituted benzoxazolesA cascade acylation-cyclization of o-bromoanilines and acyl chlorides was catalyzed by coppernanoparticles with the promotion of1,10-phenanthroline, leding to2-substituted benzoxazoles ingood to execllent yields. The reaction could be completed in a short time at90oC in acetonitrile withK₂CO₃as base instead of Cs₂CO₃. Compared to conventional methods, this reaction we reportedhererin is tolerant of a wide variety of functional groups on aromatic ring, such as methyl, methoxyl,fluoro or chloro are tolerated. Furthermore, the nanoparticle catalyst can be recycled for twice at leastwithout any significant loss in catalytic activity.（2） Copper nanoparticles catalyzed synthesis of3-substituted isocoumarinsIn the absence of ligand, the reaction of2-halogenate benzamides with1,3-dicarbonylcompounds was achieved by using copper nanoparticles as the catalyst and K₃PO₄as base under mildconditions. In contrast to previous reports, a variety of substituted starting material with bromo,chloro groups, which showed much lower activities than iodo-substituted compounds, were used inour reaction, and gave good to excellent yields.By the two novel methodologies above, thirty kinds of substituted benzoxazoles and two kinds ofsubstituted isocoumarins were prepared and characterized.