Iodine-catalyzed coupling of 4-hydroxyproline with isatins: An expeditious synthesis of 3-pyrrolyl indolin-2-ones

Molecular iodine is found to catalyze efficiently the coupling of 4-hydroxyproline with isatins under mild conditions to produce 3-(1H-pyrrol-1-yl)indolin-2-one and 11-(1H-pyrrol-1-yl)-11H-indeno[1,2-b]quinoxalin-11-one derivatives in excellent yields in a short reaction time with high selectivity. The use of iodine makes this procedure quite simple, more convenient and cost-effective.

Graphical abstractIodine is found to catalyze efficiently the coupling of 4-hydroxyproline with isatins under mild conditions to produce 3-(1H-pyrrol-1-yl)indolin-2-one and 11-(1H-pyrrol-1-yl)-11H-indeno[1,2-b]quinoxalin-11-ones in excellent yields.Figure optionsDownload full-size imageDownload as PowerPoint slide