Metal-free dearomative [5+2]/[2+2] cycloaddition of 1<i>H</i>-indoles with <i>ortho</i>-(trimethylsilyl)aryl triflates
Xinyu Chen, Na Yang, Wen Zeng, Lei Wang, Pinhua Li, Hongji Li
Abstract
Herein, we report a mild dearomative [5+2]/[2+2] cycloaddition of 1H-indoles with ortho-(trimethylsilyl)aryl triflates. The unique [5+2] cycloaddition enables the synthesis of a series of dibenzo[b,e]azepine derivatives in moderate to good yields. Increasing the steric hindrance at the C2-position of 1H-indoles leads to the [2+2] cycloaddition. Mechanistic investigations support that the reaction of 1H-indoles with arynes undergoes a [2+2] cycloaddition step, followed by a ring expansion to the [5+2] cycloaddition product.
Topics & Concepts
ArylTrimethylsilylCycloadditionChemistryMetalMedicinal chemistryCombinatorial chemistryOrganic chemistryCatalysisAlkylCatalytic C–H Functionalization MethodsCyclopropane Reaction MechanismsCatalytic Alkyne Reactions