Palladium‐Catalyzed Direct Arylations of Five‐Membered Heteroarenes Bearing N ‐Monoalkylcarboxamide Substituents

The palladium-catalyzed direct arylation of furan, thiophene, pyrrole, or pyrazole derivatives bearing CONHR substituents on C2, C3, or C5 with aryl bromides was studied. The use of KOAc as the base, DMAc as the solvent, and PdCl(C3H5)-(dppb) as the catalyst was found to give regioselectively and without decarbamoylation the arylated heteroaromatics. Under these conditions, the amide substituent on the heteroaromatic does not act as a directing group. A wide range of functional groups such as acetyl, formyl, ester, nitrile, trifluoromethyl, and fluoro on the aryl bromide is tolerated.