Oxidative Methylamination of Nitroquinolines

Abstract

Abstract 3‐, 5‐, 6‐, 7‐ and 8‐nitroquinoline as well as 5,7‐ and 6,8‐dinitroquinoline are methylaminated with a liquid methylamine solution of potassium permanganate (LMA/PP) to the corresponding mono‐ and bis(methylamino)‐substituted compounds. 2‐Nitroquinoline is aminated with LMA/PP to 2‐(methylamino)quinoline. The intermediate methylamino σ‐adducts of 3‐nitro‐ and 5,7‐ and 6,8‐dinitroquinoline are detected by 1 H‐NMR spectroscopy. Quantum chemical calculations for the mononitroquinolines suggest that the experimentally observed regioselectivity of the methylamination is controlled by an interaction of frontal molecular orbitals (FMO) of the reagents.