Visible-light-induced Controllable Reactions Of Quinoxaline-2(1H)-ones With Organoboronic Acids

Quinoxalin-2（1H）-one derivatives represent a privileged class of nitrogen containing heterocycles with biological activity,because the compounds have one or more reactive sites,it is convenient to synthesize a series of compounds with different bioactivity,and it has been widely used in drug molecules.The bioactivity of quinoxa-lin-2（1H）-one depends on its C-3 functional groups.Affected by this,the C-3 functional group has have attracted increasingly attention from chemists in recent years,the diversity of C3-substituted quinoxalin-2（1H）-ones has improved the application in medicinal chemistry.The substitution at the C-3 position is considered to be the most direct and effective method of functionalization was reported.In this work,quinoxalin-2（1H）-one with alkylboronic acid’s reaction is controlled by atmosphere（nitrogen or oxygen）.The details of this study as follows:1.The reaction of 1-methylquinoxalin-2（1H）-one and alkylboronic acids was carried using N,N-dimethylformamide（DMF）as solvent in the absence of any pho-tocatalyst at room temperature under air atmosphere visible-light irradiation conditions,providingthecorrespondingC3-alkalated 1-methylquinoxalin-2（1H）-ones in good yields.2.The reaction of 1-methylquinoxalin-2（1H）-one and alkylboronic acids was performed by N,N-dimethylformamide（DMF）as solvent without any photocatalyst at room temperature in nitrogen atmosphere under visible-light irradiation conditions,generating the desired C=N addition products of 1-methylquinoxaline-2（1H）-ones in high yields.The above reactions have the advantages of cheap and readily available substrates,no external additives and photocatalysts needed in the reaction,and mild reaction conditions with high product yields.In addition,the structures of the obtained products were characterized by ¹H NMR,¹³C NMR and single crystal X-ray diffraction analysis.It should be noted that the possible reaction mechanism was proposed by the capture reaction of free-radicals.