Palladium-Catalyzed Direct Arylation of Free NH₂-Substituted Thiophene Derivatives

Abstract

The palladium-catalyzed direct 2- or 5-arylation of some free NH(2)-substituted thiophene derivatives was found to proceed in high yields using a variety of aryl bromides. In the course of these reactions, no coupling of the aryl bromide with the thiophene NH(2) substituent was detected. The presence of an ester substituent on C2 of thiophene was found to be useful to block this highly reactive carbon.