Cobalt-catalyzed coupling of alkyl Grignard reagent with benzamide and 2-phenylpyridine derivatives through directed C-H bond activation under air

Aromatic carboxamides and 2-phenylpyridine derivatives can be ortho-alkylated with Grignard reagents in the presence of a cobalt catalyst and DMPU as a ligand. The reaction proceeds smoothly at room temperature, using air as the sole oxidant. The dialkylated product is selectively obtained when N-methylcarboxamide is employed as a substrate, whereas N-phenyl- or N-isopropylcarboxamide preferentially gives the monoalkylated product.