Zirconium nitrate: a reusable water tolerant Lewis acid catalyst for the synthesis of N-substituted pyrroles in aqueous media

Abstract

A simple, efficient procedure for the synthesis of 11-(1H-pyrrol-1-yl)-11H-indeno[1,2-b]quinoxaline and 3-(1H-pyrrol-1-yl)indolin-2-one derivatives in aqueous media is described. The condensation reaction between 4-hydroxyproline and isatin derivatives or 11H-indeno[1,2-b]quinoxalin-11-ones, using a catalytic amount of Zr(NO₃)₄ as a water tolerant Lewis acid catalyst affords, the title compounds in high to excellent yields and in short reaction times.