Electrochemically time-dependent oxidative coupling/couplingcyclization reaction between heterocycles:tunable synthesis of polycyclic indole derivatives with fluorescence properties

A mild and practical protocol for selectively time-dependent dehydrogenative C–C coupling,as well as tandem couplingcyclization reaction between indoles or/and other heteroaromatics via electrochemically oxidative process has been demonstrated.The reaction runs under noble catalyst,external oxidant and inert gas free condition,allowing tunable access to a wide variety of synthetically useful symmetrical or nonsymmetrical heteroarene with aggregation-induced emission(AIE),and polycyclic 3-D indole derivatives with aggregation-caused quenching(ACQ)fluorescence properties.Finally,preliminary mechanistic study indicated that tunable generation of indole cation under various electrolysis potential via regulating Nprotecting group was the key to achieve cross-coupling between indoles and other heteroaromatics.