Visible Light Induced The Synthesis Of Imidazole And Oxazoline Derivatives

Heterocycles play an important role in organic synthesis, and have a promising future in pesticides as well as Pharmaceuticals. Among them, H-containing heterocycles have been widely used in pesticide, medicine and other chemical industry, they have became more and more important in modern medical and new pesticide research. Imidazole and oxazoline compounds are an important class of five-membered N-containing heterocycles which contain biological and pharmacological activities, and also they are widely used in the field of asymmetric synthesis. Accordingly, it is highly desirable for chemists to search for more efficient and operationally simple processes for the rapid synthesis of diversely functionalized imidazole and oxazoline derivatives.In nineteenth Century seventy years, visible light has gradually been concerned by the people and been widely applied to organic synthesis. In recent years, the visible light photocatalysis has become the current hot research fields, it’s a practical method for the synthesis of the useful compounds. In this paper, we have introduced the latest research progress in the visible light photocatalysis, based on this strategy, we successfully achieved the rapid synthesis of imidazole and oxazoline derivatives.First of all, we developed a visible-light-induced phtotocatalytic aerobic oxidation/ [3+2] cycloaddition/aromatization cascade. The reaction provides a general and efficient access to diversely substituted imidazoles and imidazo[1,5-a]quinoxalin-4(5H)-ones under very mild conditions. The secondary amines generated imines under the irradiation of visible light, then reacted with isocyanide through [3+2] cycloaddition to get the imidazole derivatives with high yields. Based on the literatures and the control experiment, we proposed a possible mechanism of this reaction.Secondly, we achieved a visible-light-induced photocatalytic oxytrifluoro-methylation of N-allylamides, it is a efficient access to the corresponding highly functionalized CF3-containing oxaolines and benzoxazines in generally high yields. Moreover, the use of diethyl 2-bromomalonate as the radical source also gave the corresponding oxazolines and benzoxazines with good yields. Based on the literatures and the experiment results, a possible mechanism involving radical process was also proposed for the reaction. Further expand the use of this methodology as well as the biological evaluation of those products are underway in our laboratory.