Two-pot synthesis of indolizinoindole derivatives via lewis acid-mediated intramolecular regioselective cyclization of 3-acylpyrroles

Abstract

A two-pot method has been developed to access indolizino[8,7-b]indole derivatives through Lewis acid-mediated regioselective C5-cyclization of 3-acylpyrrole prepared from the feedstock materials. The overall reaction proceeds through amine-catalyzed direct aldol reaction/Paal-Knorr reaction/oxidation between succinaldehyde, aromatic aldehyde, and tryptamine in a sequential multicomponent fashion for N-alkyl pyrrole followed by dearomative cyclization. A series of substituted indolizino[8,7-b]indoles have been prepared with good yields and excellent regioselectivity.