Dy(OTf)3 as a versatile catalyst for the synthesis of 3-pyrrolyl-indolinones and pyrrolyl-indeno[1,2-b]quinoxalines

Dysprosium(III) triflate is found to catalyze efficiently the coupling of 4-hydroxyproline with indeno[1,2-b]quinoxalin-11-one and isatin derivatives under mild conditions to produce 11-(1H-pyrrol-1-yl)-11H-indeno[1,2-b]quinoxalin-11-one and 3-(1H-pyrrol-1-yl)indolin-2-one derivatives, respectively, in excellent yields in short reaction times. A comparative study with both InCl3 and Dy(OTf)(3) is described. (c) 2007 Published by Elsevier Ltd.