Selective Heteroaryl N-Oxidation of Amine-Containing Molecules.

The first examples of nonenzymatic N-oxidation of heteroarenes in the presence of amines are reported. Pyridine, quinoline, and isoquinoline N-oxides are selectively formed in the presence of more reactive aliphatic and alicyclic amines by use of an in situ protonation strategy and an iminium salt organocatalyst. Application to late-stage functionalization that mimics phase 1 metabolism of small-molecule drugs is also demonstrated.