Study On The Coupling Reactions Of Arylhydrazines

Purpose: Arylhydrazines are very important organic materials and synthetic intermediates that are widely involved in various organic transformations.To further investigate the reactive profiles of arylhydrazines as novel aryl donors,two types of coupling reactions were developed in this dissertation,including the Mizoroki-Heck coupling reaction and the regioselective arylation of benzofurans,which could provide convenient and efficient procedures for the preparation of related functional building blocks.Methods: In this study,N'-acyl arylhydrazines were used as novel arylating agents and two aspects of research work were revealed as follow: 1.A novel type of Mizoroki-Heck reaction was realized with N'-acyl arylhydrazines and olefins as coupling partners under transition-metal catalyzed conditions.The reaction was performed using 5 mol% Pd Cl₂ and 10 mol% Cu I as co-catalysts,2.0 equiv,TFA as an additive,DMSO?2.0 m L?as solvent,and various corresponding aryl olefin products were obtained efficiently in good to excellent yields.2.Using N'-acyl arylhydrazines as aryl donors,the regioselective C-2 arylation of benzofurans was developed under transition-metal catalyzed conditions.Using 15 mol%Pd Cl₂?Me CN?₂ as catalyst,3.0 equiv.TEMPO as oxidant,various functional groups substituted benzofurans were converted 2-aryl benzofurans smoothly under the optimal reaction conditions.Results: 1.With N'-acetyl phenylhydrazine and styrene as model substrates,the optimal reaction conditions were established through comprehensive invesitgation of the catalysts,additives and solvents.Subsequently,we have examined the scope of substrates via 36 examples.Meanwhile,the possible catalytic mechanism of this coupling reaction was proposed through the controlled experiments.The developed procedure does not require external ligands and oxidants,and has the advantages of high reaction yields,good chemoselectivity and regioselectivity,and wide substrate scope.2.Using N'-acetyl phenylhydrazine and benzofuran as model substrates,the optimal reaction conditions were established bycareful screening of palladium salts,oxidants and solvents and the functional group tolerance was examined via 29 examples.In addition,our developed method was successfully applied to the preparation of potent bioactive candidates and achieved good results.Through the controlled experiments,we have also proposed the possible mechanism for this coupling reaction.This protocol features highly regioselective products and good functional group tolerance.Conclusions: Using N'-acyl arylhydrazines as novel aryl donors,and two types of methodologies have been developed with wide application and practical value,which could provide convenient and efficient approaches for the rapid construction of releated functional structural units.Meanwhile,the accomplishment of this research will broaden the application scope of arylhydrazines as novel,green arylating reagents in the field of arylation coupling reactions,and provide theoretical reference for subsequent related research.