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

Abstract

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