Direct Amidation of 2-Methylquinolines With Anilines Under Transition-Metal-Free Conditions Using Air as the Sole Oxidant

A facile oxidative coupling of 2-methylquinolines with anilines that uses air as the sole oxidant is described. The reaction affords a straightforward route to aromatic amides under transition-metal-free conditions. With potassium tert-butoxide as the promoter, the direct amidation reaction proceeds smoothly at a lower reaction temperature relative to reported protocols (75°C vs. 120°C–130°C). Notably, the replacement of 2-methylquinoline with 2-quinolinecarboxaldehyde, a putative intermediate in previous studies, for the coupling with aniline resulted in a markedly lower yield of the target aromatic amide (59% vs. 84%). This unexpected finding offers new possible considerations for relevant research in organic chemistry.