Study On Visible Light-Mediated Synthesis Of Indole Carbazole Alkaloids

Indole carbazole alkaloids have remarkable activity in the inhibition of protein kinase and topoisomerase.The modified indole carbazole alkaloids can be used in medicine,agriculture and other fields,which have attracted the attention of many chemists and pharmacologists.In this dissertation,we have developed a novel method of preparing indole carbazole alkaloids mediated by visible light,that is using iridium catalysis to catalyze benzene free radical generated by N-allenyl-2-iodoaniline compound to generate intramolecular free radical,then indole cyclization/dimerization and deprotection under acidic conditions /intramolecular by Mannich cyclization to realize efficient synthesis of indole carbazole alkaloids.The dissertation is divided into two parts:In the first part,indole carbazole alkaloids are briefly introduced,especially the synthesis progress of these compounds are systematically reviewed.The second part mainly introduces a novel method of synthesizing indole carbazole alkaloid skeleton.N-allenyl-2-iodoaniline compound,which is simple and easy to prepare,is used as the substrate,and the free radical tandem cyclization reaction is taken as the key step under the irradiation of visible light to realize the novel and efficient construction of indole carbazole alkaloid core skeleton.At the same time,we investigated the universality of the reaction,and completed the preparation of indole carbazole alkaloids with 18 different substituents,and realized the synthesis of tjipanazole B and D,natural products of indole carbazole.On the basis of detailed research,we proposed a possible reaction mechanism for this reaction: iodobenzene substrate was reduced to benzene free radical under visible light irradiation,and then reacted with the intermediate carbon of allene to generate 3-methylindole free radical,followed by free radical dimerization and deprotection under acidic conditions/intramolecular Mannich cyclization,finally realizing the synthesis of indole carbazole alkaloids.Compared with the existed synthesis methods,this method has greater novelty and advantages,and provides a new idea for the diversified preparation of indole carbazole alkaloid products.