Palladium-Catalyzed Buchwald-Hartwig Coupling of Deactivated Aminothiophenes with Substituted Halopyridines

The palladium‐catalyzed Buchwald–Hartwig coupling of several deactivated aminothiophenecarboxylates with differently substituted halopyridines has been performed for the first time by using Pd(OAc)2, Xantphos as the ligand, and Cs2CO3 as the base. When 2,6‐dihalopyridines were used, the proportion of diaminated product increases with the reactivity of the halopyridines (iodo > bromo > chloro). A bromo monoaminated pyridine derivative, obtained by Buchwald–Hartwig coupling, was further used in the Suzuki coupling of aryl boronic acids bearing electron‐withdrawing or electron‐donating groups. These latter compounds are very interesting as they possess diheteroarylamine and heteroaryl–aryl skeletons including pyridine and thiophene moieties.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)