Silica gel supported nitric acid treatment of 2, 5-dimethoxybenzaldehyde followed by reduction with iron powder provides 3, 6-dimethoxy-2-aminobenzaldehyde. Friedlinder condensation of this species with a variety of ketones and diketones leads to 5, &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 ...