I₂-Catalyzed Synthesis Of Pyridoimidazoles Compounds

In 1925,the imidazopyridine ring system was first described by Chichibabin.However,the research on this skeleton has been rare for a long time,due to the lack of effective functionalization methods to prepare structural variants.In this paper,the synthesis methods and overviews of imidazo[1,5-a]pyridine and its derivatives are mainly discussed.The paper is divided into four parts.Firstly,the 1,3-dipolar cycloaddition provides a very powerful support for the synthesis of five-membered heterocycles.Among of them,the 1,3-dipole especially azomethine ylides,which can easily construct a nitrogen-containing five-membered heterocyclic compounds.Therefore,we have summarized and concluded the work of the predecessors in the paper.Secondly,the imidazole ring,which is a histidine moiety,has a widely application in many biologically important molecules.The pyridoimidazole ring's structure,the parent molecule belongs to the aromatic heterocyclic ring,scientists have gradually discovered its shining point in various fields.Here we briefly discuss it.Thirdly,I₂/TBPB catalyzed the synthesis of imidazo[1,5-?]pyridine from azomethine and pyridine in a solvent of acetonitrile.This method successfully solves the limitations of metal catalysis using metal-free catalysis.And accompanied by good yield.Lastly,I₂ catalytzed oxidation of 2-Pyridyl Ethyl Acetate and Benzylamine.The synthesis of pyrido[1,5-a]imidazoles in dichloromethane.The reaction does not require metal catalysis,the conditions are mild and simple,and the yield is high.