Homolytic Substitution Reactions of Electron-Rich Pentatomic Heteroaromatics by Electrophilic Carbon-Centered Radicals. Synthesis of α-Heteroarylacetic Acids

Abstract

Efficient and selective homolytic substitutions (yields between 55 and 90%) of pyrrole, indole, and some pyrrole derivatives have been carried out using ambiphilic and electrophilic carbon centered radicals, generated in DMSO by Fe2+/H2O2 and α-cyano-, α-carbonyl-, and α,α′-dicarbonylalkyl iodides. The reaction is highly successful also with pyrroles substituted by electron-withdrawing groups, which has allowed an efficient synthesis of Tolmetin. A few extensions of this reaction to furan and thiophene are described. © 1992, American Chemical Society. All rights reserved.