Synthesis of bridged azaheterocycles peri-annulated to the indole core
摘要
The domino reaction of 2-(1-methyl-3-formylindol-4-yl)cyclopropane-1,1-dicarboxylate with benzylamines upon catalysis by gallium triflate gave two types of tetracyclic systems containing bridged azabicycles peri-annulated to the indole core. The reaction proceeded via the formation of intermediate imines, which underwent stepwise (3+2)-cross-cycloaddition reactions under conditions of the process, wherein the first step is the attack by the iminium nitrogen atom at either methylene or methine carbon atom of the small cycle.