Highly efficient synthesis of 3-pyrrolyl-indolinones and pyrrolyl-indeno[1,2-b]quinoxalines catalyzed by heteropolyacids

Simple and improved conditions have been found for the synthesis of 3-pyrrolyl-indolinones and pyrrolyl-indeno[1,2-b]quinoxalines by coupling of 4-hydroxyproline with isatins and 11H-indeno[1,2-b]quinoxalin-11-ones using Keggin (H(3)PW(12)O(40) and Well-Dawson tungsten heteropolyacids (H(6)P(2)W(18)O(62)). (c) 2008 Elsevier Ltd. All rights reserved.