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.
Phosphomolybdic Acid/SiO<sub>2</sub> as Heterogeneous Solid Acid Catalyst for the Rapid Synthesis of <i>N</i>-Substituted Pyrroles
efficiently with 4-hydroxyproline in the presence of 10 mol% of PMA/SiO2 in acetonitrile/water (4:1) under reflux conditions to furnish N-substituted pyrroles in excellent yields. Similarly, 11H-indeno[1,2-b]quinoxalin-11-ones also participated in this reaction.