Transition-Metal-Free Synthesis of N-Aryl Hydroxamic Acids via Insertion of Arynes

An efficient and transition-metal-free N-arylation of amides via the insertion of arynes into the N-H bonds in the N-alkoxy amides is described. A variety of the reactive functional groups including the reactive aldehyde carbonyl group, furan ring, carbon-carbon double bonds, and free N-H bond of indole are found to be compatible with this process. In particular, the protocol is applicable in the synthesis of structurally diverse N-aryl hydroxamates and hydroxamic acids derived from N-protecting amino acids and peptides. In the presence of multiple amide N-H bonds, the N-arylation reaction can proceed selectively in the N-H bonds of terminal N-OBn amides giving rise to the desired N-aryl hydroxamates.