Incorporation of Quinoline-5,8-quinone Moiety into Polyaza Cavities

Article abstract of DOI:10.1021/jo00059a012

Silica gel supported nitric acid treatment of 2,5-dimethoxybenzaldehyde followed by reduction with iron powder provides 3,6-dimethoxy-2-aminobenzaldehyde.Friedlaender condensation of this species with a variety of ketones and diketones leads to 5,8-dimethoxyquinoline derivatives which may be oxidized by ceric ammonium nitrate (CAN) and pyridine-2,6-dicarboxylic acid N-oxide (PDANO) to the corresponding quinones.The quinone functionality can be incorporated into larger cavities by a selective stepwise Friedlaender approach and the CAN/PDANO oxidation appears to work preferentially for 5,8-dimethoxyquinoline.