Visible Light Induced Acylation Reaction Without Additional Photocatalyst

In recent years,visible light-induced organic synthesis has become a new effective method for the construction of organic compounds.Amide compounds are found in many natural products,pharmaceuticals and polymers.Conventional acylation reactions often require transitional metal catalysts,strong oxidants,high temperature and other harsh reaction conditions.Compared with conventional acylation reactions,visible light induced acylation reaction has unique advantages: The reaction can be carried out at room temperature,the conditions are simple,mild and efficient,avoiding additional ligands or additives.The reaction is gradually carried out in the direction of without additional photocatalyst.There are few reports on visible light-induced acylation reactions without additional photocatalyst.Based on the above understanding of the acylation reaction.In this paper,different types of acylation reactions were achieved by visible light-induced without additional photocatalyst.The main research contents are as follows:(1)A novel and practical hypervalent iodine(III)reagent catalyzed decarboxylative formation with ?-keto acids and acrylamides by blue LED(450–455 nm)irradiation at room temperature has been established.In the reaction system,there is no additional photocatalyst and oxidant.The by-product is carbon dioxide.The experiment condition is simple and mild.Mechanistic study demonstrates that the decarboxylation undergoes a radical process by visible-light irradiation.Ester high iodine reagent with ?-keto acid to form intermediate,the intermediate homolytic by visible light-induced.Then release carbon dioxide and form acyl radicals.The reaction finished by free radical cyclization.(2)A visible light induced oxidative formylation of N-alkyl-N-(prop-2-yn-1-yl)anilines with molecular oxygen in the absence of external photosensitizer was developed,which afforded the corresponding formamides in good yields under mild conditions.Mechanism investigation disclosed that both starting materialand product act as photosensitizers,and 1O2 and O2·-are generated in the reaction through energy transfer and single electron transfer pathway.