Efficient Aliphatic C-H Bond Oxidation Catalyzed by Manganese Complexes with Hydrogen Peroxide

A tetradentate nitrogen ligand containing a benzimidazole ring and an electron-rich pyridine ring was developed, the resulting manganese complex exhibited good activity in the C-H oxidation of simple alkanes. In particular, cyclic aliphatic alkanes were transformed into ketones in very good yields (up to 89 %) by using environmentally benign H₂ O₂ as the terminal oxidant. This protocol was also applied successfully in benzylic C-H oxidation, giving the corresponding ketones with very good selectivities. In addition, tertiary C-H bond oxidation of complex molecules by the manganese complex showed potential utility for assembling alcohols with good selectivity in late-stage chemical synthesis.