Font Size: a A A

Synthesis Of Substitued Pyrazole Acids And Carbon-Nitrogen Coupling Reaction Research

Posted on:2013-11-10Degree:MasterType:Thesis
Country:ChinaCandidate:B J ZhangFull Text:PDF
GTID:2231330392452831Subject:Chemistry
Abstract/Summary:PDF Full Text Request
The coupling reaction is one of the important synthesis of various chemicalcompounds. This thesis contains two aspects: the first part of the importantapplications based on Suzuki coupling reaction, the synthesis of a series of pyrazoleboric acid and boric acid pinacol ester of the corresponding pyrazole. The second partof the Ullmann reaction, to explore the optimal reaction conditions of thecarbon-nitrogen coupling reaction in the condition of free catalyst ligands.Organic boric acid compounds as catalysts in many reactions (such asesterification, amidation, acetylation reaction) have obvious advantages. The organicboric acid compounds are also reactants of Suzuki coupling reaction. In addition,organic boric acid compounds based on their own nature are also applied in themolecular recognition. Heterocyclic compounds are widely found in nature, because alot of pharmaceutical intermediates with the structure of the pyrazole ring, pyrazolehas also become one of the important research for new medicine. We have synthesizeda series of alkyl-substituted pyrazole boric acids and the corresponding boric acidesters.The formation of carbon-heteratom catalyzed by transition metal is an importantresearch direction in the coupling reaction. Traditionally, it is more efficient that usingof palladium and nickel complexs catalytic reaction, but the catalysts are expensive,high toxicity which has a serious impact on their wider applications. Then peopledeveloped a variety of ligands combined with the copper salt catalyzed reactions andmade some progress. Therefore, we studied ligand-free catalyst system, and has madesome progress.We have optimized the reaction conditions of the azaheterocyclic nitrogenarylation with substituted aromatic halides: ligand free of CuI/NaH catalyst systemwith lower reaction temperature and fewer base. Aryl bromides, iodides aromatics cancouple with azaheterocyclic efficiently, and some chlorinated aromatic also be able toget a higher yield of coupling products. The catalyst can be recycled and reused manytimes, and catalytic properties could be retained.
Keywords/Search Tags:Pyrazole, Boric acid, Coulpling reaction, Catalyst
PDF Full Text Request
Related items