High Selectivity Hydroxylation and Other Functionalization of Quinoline-Directed Reactions under Cu(II)-Catalysis.

Despite progress in ortho C-H functionalization of aromatic rings directed by guiding groups, achieving highly selective hydroxylation in simple systems without the need for additional ligand assistance remains a significant challenge. Here, we report the direct hydroxylation of the ortho C-H bond of aromatic rings directed by quinoline under Cu(II) catalysis. Based on experimental analysis and DFT calculations, the main reason for the high selectivity of the quinoline-directed hydroxylation reaction is that the match between the new substrate and the method leads to an increased range of oxygen source incorporation. Isotope experiments and DFT calculations provide support for the origin of the oxygen source in the hydroxylation process and the rationale behind its observed distribution. Additionally, the introduction of various nucleophiles enabled the cyanation, nitration, and halogenation of ortho C-H bonds in the aryl group.