Lithium Perchlorate Catalyzed Reactions of Indoles: An Expeditious Synthesis of Bis(indolyl)methanes

Lithium perchlorate is found to catalyze efficiently the electrophilic substitution reactions of indoles with aldehydes and ketones in diethyl ether to afford the corresponding bis(indolyl)methanes in high yields. LiOTf is also found to be an efficient catalyst for the synthesis of these compounds.