Studies On Cyanation And Coupling Reaction Of C1-Position Of N-Aryltetrahydroisoquinoline By Visible Light

As an essential molecular skeleton structure,tetrahydroisoquinoline exists in a wide variety of bioactive natural products and drug molecules.Previously,tetrahydroisoquinoline and its derivatives were extracted from natural substances.With increasing demand,they are now produced by chemical synthesis.Nonetheless,the synthetic methods are not in line with the idea of sustainable development.It is hence commendable to develop efficient,convenient,inexpensive,and environment-benign methods for their production.Visible light is widely and easily available,and the use of this sustainable energy source has become a research focus in organic synthesis.In this project,the green generation of N-aryltetrahydroisoquinoline and its derivatives is the main goal,and two series of works were carried out to realize the construction of two types of carbon-carbon bonds for the functionalization of C1 position of N-aryltetrahydroisoquinolines.1 、 The oxidative cyanation reaction of N-aryltetrahydroisoquinoline at C1 position induced by visible light has been demonstrated.In the reaction,purple LEDs of 30 W were used as light source,oxygen as oxidant,acetonitrile as solvent,and potassium thiocyanate,which is low in toxicity and easily available,as cyano source.The reaction does not require the participation of a photocatalyst,a strong oxidizing agent,and a cyano-containing compound that is highly toxic or difficult to obtain.The method is simple,the reaction conditions are mild,the substrate adaptability is good,and the yields are medium to good.2 、 A photocatalytic method using visible light for the coupling of N-aryltetrahydroisoquinoline(at C1 position)with imidazo [1,2-a] pyridine(at C3 position)has been developed.In the reaction,Eosin Y(10 mol%)was used as photocatalyst,oxygen as oxidant,fluorescent lamp(30 W)as light source,and a mixture of acetonitrile and water as solvent.The reaction does not require a transition metal catalyst or a strong oxidant.The method is simple and green.The reaction conditions are mild,the substrate adaptability is good,and the yields are moderate to good.