Application of Nicotinic Acid Functionalized Chlorosulfonic Acid as a Green Catalyst for the Synthesis of Bis(2-methyl-1Hindole)Derivatives


Department of Chemistry, Rasht Branch, Islamic Azad University, Rasht, Iran


3-Carboxy-1-sulfopyridin-1-ium chloride ([CPySO3H]+Cl-) as a novel ionic organocatalyst for the
condensation of aldehydes and 2-methylindole to synthesize bis(2-methyl-1H-indole) derivatives in
acetonitrile at room temperature has been developed. Some tetrakis (2-methyl-1H-indole)
derivatives have also been synthesized by the reaction of 2,2'-(butane-1,4-
diylbis(oxy))dibenzaldehyde and 2-methylindole or indole in the presence of chlorosulfonic acid
immobilized on nicotinic acid ([CPySO3H]+Cl-) at room temperature. All products formed in
excellent yields over short reaction times under mild and environmentally friendly conditions. This
methodology offers significant improvements for the synthesis of bis(2-methyl-1H-indole)
derivatives with regard to the yield of products, simplicity in operation and reusability of the