Visible-light-induced Functionalizations Of Quinoxaline-2(1H)-ones

Quinoxalin-2（1H）-ones are important nitrogen-containing heterocyclic compounds,which are widely found in bioactive molecules,drugs and functional materials.They have special biological activity and chemical properties.The direct functionalization of quinoxalin-2（1H）-ones has become an important method for the construction of novel quinoxalinone derivatives.Photoinduced functionalization of quinoxalinones has become one of the important research fields in organic synthesis due to its simple operation,mild reaction conditions and wide applicability.In this paper,the C-H bond activation and bifunctionalizations of quinoxalinones’highly active unsaturated carbon-nitrogen-bond sites were studied.The acyloxynitroso compounds and oxime ester compounds were used as free radical precursors to achieve visible light-induced alkyl radicals through energy transfer.In the first chapter,the photocatalytic reaction is briefly summarized from the development of photocatalytic reaction,the type of photocatalyst and the reaction mechanism.The research progress of C3functionalizations of quinoxalinones and the bifunctionalizations of quinoxalinones by visible light catalysis in recent years are briefly introduced.In the second chapter,the photo-induced bifunctionalizations of quinoxalinones by acyloxynitroso compounds through energy transfer pathway was studied in detail.This reaction uses quinoxalin-2（1H）-ones as a substrate,acyloxynitroso compounds as free radical precursors,Ru（bpy）₃Cl₂ as a photocatalyst,DMSO:H₂O=1:1 as a solvent,under the blue light irradiation of 450-455 nm,a series of quinoxalinone derivatives can be obtained in moderate to good yields at room temperature for 3 hours.This reaction can further achieve gram-scale reaction and further conversion of the product.In the third chapter,the C3 alkylation reactions of quinoxalinones with oxime ester as free radical source under visible light catalysis by energy transfer pathway was studied in detail.The reaction used quinoxalin-2（1H）-ones as substrates,amino acid oxime esters as free radical precursors,9-thioxanthone as photosensitizer,DCM as solvent,under the illumination of 395-405 nm.The related derivatives of quinoxalinone were obtained in moderate to good yields.