In 5 ml of dimethylformamide was dissolved 1 g of 2-amino-4-(4-methoxyphenyl)-5-(3-pyridyl)-1,3-thiazole. To the solution was added under ice-cooling 580 mg of ethoxycarbonylacetylchloride. The mixture was stirred for 30 minutes, to which was then added a saturated aqueous solution of sodium hydrogen chloride. The resultant was subjected to extraction with ethyl acetate. The organic layer was washed with water, dried and concentrated, followed by recrystallization from tetrahydrofuran to give 850 mg (61%) of 2-ethoxycarbonylacetylamino-4-(4-methoxyphenyl)-5-(3-pyridyl)-1,3-thiazole, m.p. 202°-203° C.
