Photocatalytic Synthesis Of Benzotriazine And Benzocarbazole Derivatives

Visible light-driven photochemical synthesis has attracted great interest from academia and industry due to its low cost,safety,green,sustainable characteristics.1,2,4-Benzotriazine and benzo[a]carbazoles derivatives are widely used in medicine,pesticide,materials,chemical industry and other fields.It is of great significance to develop new photochemical synthesis methods to realize the efficient synthesis of1,2,4-benzotriazine and benzo[a]carbazoles derivatives which have important application value.This thesis aims at the synthesis researches of 1,2,4-benzotriazine and benzo[a]carbazoles derivatives by visible light catalysis,and the paper includes the following three parts.Chapter 1.This chapter mainly introduces the background,catalytic mechanism as well as decarboxylation of carboxylic acids and their derivatives by visible light catalysis.Chapter 2.The decarboxylation cascade cyclizations of α-imino acids and azodicarboxylate esters catalyzed by cheap and available organic dye photocatalysts were successfully developed,and a series of 1,2,4-benzotriazine derivatives were synthesized in medium to excellent yields.The Boc group can be easily removed to give 1,2,4-benzotriazine.This is the first example of synthesis of 1,2,4-benzotriazines by visible light catalysis.In addition,it is characterized by mild conditions,good substrate applicability and scale-up synthesis.The results provide a simple and efficient route for the synthesis of 1,2,4-benzotriazine derivatives.Chapter 3.The free-radical cascade cyclizations of indole derivatives and α-bromo-α,β-unsaturated aldehydes catalyzed by visible light were developed.In addition,the structure of the reaction product can be effectively controlled by fine tuning of the reaction substrate and a series of formyl substituted benzo[a]carbazole and benzo[e]-indole derivatives with wide application value were synthesized in medium to good yields.Moreover,the methods don’t need to use transition metal,and the raw material is easy to recover.The research provides a new approach for the synthesis of benzocarbazole and benzoindole derivatives.