Tandem [2 + 2] Cycloaddition/Rearrangement toward Carbazoles by Visible-Light Photocatalysis
Chengjuan Wu, Wenxiao Cao, Bin Chen, Chen‐Ho Tung, Li‐Zhu Wu
Abstract
Reported herein is the first example of the synthesis of carbazoles via oxidative cyclization of 3-alkenylindoles with styrenes under visible light. The irradiation of a catalytic amount of [Ir(dtbbpy)(ppy)2][PF6] as the photocatalyst enables various 3-alkenylindoles and styrenes to undergo tandem [2 + 2] cycloaddition/rearrangement, thereby leading to carbazole derivatives in good to excellent yields under aerobic conditions. Mechanistic studies reveal that photoinduced energy transfer followed by electron transfer is responsible for the tandem reaction.
Topics & Concepts
TandemCycloadditionChemistryPhotocatalysisPhotochemistryCarbazoleCatalysisElectron transferIrradiationVisible spectrumPhotoinduced electron transferCascade reactionOxidative phosphorylationCombinatorial chemistryOrganic chemistryComposite materialBiochemistryNuclear physicsMaterials scienceOptoelectronicsPhysicsRadical Photochemical ReactionsCatalytic C–H Functionalization MethodsSulfur-Based Synthesis Techniques