KHSO4-SiO 2 catalyzed facile synthesis of bis(indolyl)methanes

This work presents a highly efficient and simple method for the synthesis of bis(indolyl)methanes, catalyzed by KHSO 4-SiO 2 with excellent yields. Various substituted aldehydes with indole under this reaction condition is elucidated. This method is an environmentally benign, efficient reaction, requires shorter reaction time and simple experimental and workup procedures.