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.