Phosphomolybdic Acid/SiO₂ as Heterogeneous Solid Acid Catalyst for the Rapid Synthesis of N-Substituted Pyrroles

Abstract

Isatins react 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.

Keywords:

• Heteropoly acid
• 4-hydroxy proline
• isatins
• pyrroles

ACKNOWLEDGMENTS

The authors express thanks to Prof. C. Devendranath Reddy and Dr. C. Naga Raju, Department of Chemistry, S. V. University, Tirupati, for their helpful discussions, and the director, Indian Institute of Sciences, Bangalore, India, for providing the spectral data.

Notes

^a All products were characterized by IR, ¹H NMR, ¹³C NMR, and mass spectroscopy.

^b Yields of pure products after chromatography.