Study On The Cyclization Reaction Of α-Diazoesters Catalyzed By Copper

Diazo compounds are an important class of organic compounds in modern organic synthesis,which are widely applied to various types of organic conversion reactions to construct a wide variety of chemical bonds and greatly enrich carbene chemistry.The transition-metal-catalyzed formation of metal carbene intermediates from diazo compounds has always been a hot topic for organic chemists,especially copper salts as favorable catalysts.In this thesis,a series of important organic compounds were successfully synthesized by using copper salt as the catalyst and diazo compounds as an efficient synthon.The obtained results are showed as followed:1.We have successfully developed a copper-catalyzed three-component cyclization reaction for the synthesis of indolizine compounds under mild conditions using pyridine,electron-deficient olefins,and diazo reagents.This process undergoes in situ generation ylide intermediate from copper carbene and pyridine and the subsequent oxidation/aromatization to deliver the final products.This methodology features commercially available inexpensive catalysts and starting materials,operational simplicity,and a wide substrate scope(pyridine system,quinolone system,and isoquinoline system).In addition,this reaction has provided a new mentality for the generation of pyridinium ylides and is conducive to develop more types of catalytic reactions with different substrates.2.A three-component cyclization reaction has been successfully achieved for the direct construction isoxazolines using copper salt as the catalyst with olefins,tert-butyl nitrite,and diazo compounds.Investigation of the mechanism suggested that inexpensive and readily available tert-butyl nitrite provides a suitable source of nitrogen and oxygen,and subsequently interaction with copper carbene to efficiently form C–O,C–C,and C=N bonds.The protocol features a wide range of substrates(including aliphatic olefins and aromatic olefins),good functional group compatibility,readily available starting materials,and gram-scale.3.A novel method for the in situ formation of nitrile oxide intermediates by copper carbene and tert-butyl nitrite and the subsequent cycloaddition reaction with β-keto esters to construct isoxazoles with high selectivity.The control experiments and theoretical calculations suggested that nitrile oxide is the key intermediate in this transformation.In addition,this methodology is distinguished by the generation of nitrile oxide intermediates in organic synthesis.