Research On Functionalization Reaction Of Indole Derivatives

Indoles as a kind of important nitrogen heterocyclic compounds,widely exist in natural products and drug molecules.Due to its unique pharmacological activity and biological activity,indoles and its derivatives are widely used in medicine,pesticides,dyes,spices,fine chemical industry,and closely related to people's daily lives.Baeyer achieved the chemical synthesis of indole for the first time since 1886,The preparation of indole ring and further functions is one of the most exciting research topics in organic chemistry and has been attracted sustained attention.This paper researches on the functionalization of indole derivatives by using indoles,ketones and olefin derivatives as raw materials.The detailed researches were described as follows:1.A novel palladium catalyzed approach to 3-arylindoles was developed from indoles and cyclohexanones.Various cyclohexanones acted as aryl sources via an alkylation and dehydrogenation sequence using molecular oxygen as thehydrogen acceptor.This method showed good regioselectivity and afforded 3-arylindoles as the sole products.2.An efficient one-pot two-step indole-to-carbazole strategy has been developed.This transition metal-free methodology uses oxygen as the sole oxidant and starts from cheap and readily available indoles,ketones,and alkenes.The present protocol efficiently enables the assembly of a diverse array of substituted carbazole products with good regioselectivity and broad tolerance of functional groups.3.An efficient one-pot indole-to-carbazole strategy with cyclohexanones as the aryl source is described.This cascade carbazole formation is enabled by the NH4I-catalyzed annulations of indoles,cyclohexanones,and alkenes and subsequent dehydrogenative aromatization.The present work provides a modular synthesis of arylcarbazoles,benzocarbazoles,and naphthocarbazoles with excellent regioselectivi-ty and broad functional group tolerance.4.With unusual aliphatic migration process,an efficient one-pot two-step indole-to-carbazole strategy has been developed.This methodology uses oxygen as the sole oxidant and starts from cheap and readily available indoles,ketones,and butyl methacrylate.And this transition metal-free methodology has excellent regioselectivity and broad functional group tolerance.5.An efficient indole-to-carbazole strategy has been developed under metal-free conditions.This carbazole formation was highly promoted by NH4I with high regioselectivity through formal[2+2+2]annulation of indoles,ketones,and nitroolefins.It thus conveniently enabled the assembly of a large number of diversified carbazole products with good tolerance of a broad range of functional groups.