ZrOCl2·SiO2-catalyzed synthesis of bis(indoles) via conjugate addition of indole with electron-deficient alkenes in water

This report provides a description of an efficient and environmentally benign procedure for the synthesis of bis(indole) derivatives via reaction of indole with electron-deficient alkenes. The remarkable advantages of this method for obtaining bis(indoles) are the simplicity of the experimental procedure, short reaction times, and high yields with the green aspects by avoiding toxic catalysts and solvents.