4-Methoxycinnamic acid (178 mg, 1.0 mmol) and thionyl chloride (480 mg, 4.0 mmol) were heated under reflux for 2 hours. The excess thionyl chloride was distilled off. The resulting residue was dissolved in pyridine (1 ml). Under an ice cooling, the resulting solution was added to a solution of 5-amino-2-(4-chloro-2-methoxyphenyl)-4-methylthiazole (254 mg, 1.0 mmol) prepared in the Step 28-1-2 in pyridine (4 ml). After the removal of the ice bath, the mixture was stirred for 16 hours at a room temperature. To the mixture, 3.5% hydrochloric acid was added, and the resulting mixture was subjected to extraction with chloroform. The extract was washed with water. The washed product was dried over anhydrous magnesium sulfate, and the solvent was distilled off. The resulting residue was purified by silica gel column chromatography (chloroform:methanol=30:1) to give the title compound (54 mg, 13%).
