2-[4-(Octyloxy)phenyl]acetic acid (0.900 g, 3.40 mmol) was dissolved in tetrahydrofuran (11 ml), and 1,1′-carbonyldiimidazole (0.622 g, 4.09 mmol) was added thereto. The imidazole mixture was stirred for 1 hour at 0° C. Sodium hydride (60% oil suspension 0.136 g, 3.40 mmol) was suspended in tetrahydrofuran (11 ml), and 3-amino-1,2,4-dithiazole-5-thione (0.511 g, 3.40 mmol) was added thereto. After being stirred for 30 minutes at 0° C., the reaction mixture, with the imidazole mixture added thereto, was stirred for 3 hours at 0° C. The mixture, with water added thereto, was extracted with ethyl acetate. The organic layer was washed with saturated brine, dried over MgSO4, and then concentrated. The obtained residue was purified by silica gel column chromatography (chloroform), to give 2-[4-(octyloxy)phenyl]-N-(3-thioxo-3H-1,2,4-dithiazol-5-yl)acetoamide (Compound 6) (0.290 g, 21%).
