To a solution of 2-{4-[(2,4-dioxo-1,3-thiazolidin-5-yl)methyl]phenoxy}-N-(5-methoxy-2-nitrophenyl)-N-methylacetamide (444.7 mg) in a mixed solvent of methanol (20 ml) and dimethylacetamide (5 ml) were added successively concentrated hydrochloric acid (0.344 ml) and a 10% wet palladium-carbon catalyst (244 mg). The atmosphere in the reaction flask was replaced with hydrogen gas (5 kg/cm2), and the resulting mixture was shaken at 50° C. for 3.5 hours. After shaking, the reaction mixture was cooled to room temperature and filtered to obtain a pale yellow filtrate. When the filtrate obtained was concentrated to about 5 g, the product crystallized out of solution. The crystals precipitated were collected by filtration and washed with methanol to afford the title compound (210 mg, yield: 48%) as a white crystalline solid.
