Remote, Late-Stage Oxidation of Aliphatic C-H Bonds in Amide-Containing Molecules

Amide-containing molecules are ubiquitous in natural products, pharmaceuticals, and materials science. Due to their intermediate electron-richness, they are not amenable to any of the previously developed N-protection strategies known to enable remote aliphatic C-H oxidations. Using information gleaned from a systematic study of the main features that makes remote oxidations of amides in peptide settings possible, we developed an imidate salt protecting strategy that employs methyl trifluoromethanesulfonate as a reversible alkylating agent. The imidate salt strategy enables, for the first time, remote, nondirected, site-selective C(sp³)-H oxidation with Fe(PDP) and Fe(CF₃PDP) catalysis in the presence of a broad scope of tertiary amides, anilide, 2-pyridone, and carbamate functionality. Secondary and primary amides can be masked as N-Ns amides to undergo remote oxidation. This novel imidate strategy facilitates late-stage oxidations in a broader scope of medicinally important molecules and may find use in other C-H oxidations and metal-mediated reactions that do not tolerate amide functionality.