1080-79-1

50-00-0

87-91-2

1080-79-1

Diethyl 1H-imidazole-4,5-dicarboxylate was synthesized as follows (Ref. Example 3): under non-shade conditions. Diethyl L-(+)-tartaric acid (2.0 g) was dissolved in ethyl acetate (34.2 ml), 1,3-dibromo-5,5-dimethylglycolide (3.3 g) was added, and the reaction solution was stirred for 3 hours at room temperature. Subsequently, acetic acid (17 ml) was added to the reaction solution, followed by the slow addition of 36% aqueous formaldehyde solution (3.45 ml) under cooling in an ice bath, keeping the internal temperature at 10°C or lower. Ammonium acetate (17.2 g) was added under the same temperature conditions. The reaction solution was stirred at room temperature for 30 minutes, then warmed up to 50°C and continued stirring for 3 hours. After completion of the reaction, 5N sodium hydroxide solution was added to the reaction solution and the aqueous layer was extracted with ethyl acetate. The organic layers were combined and dried with anhydrous magnesium sulfate. The ethyl acetate solution was quantitatively analyzed by HPLC to obtain the title compound 1H-imidazole-4,5-dicarboxylic acid diethyl ester (1.24 g, yield: 60%).The HPLC analysis conditions were the same as in Example 5. The results with reference to Example 3 and Example 5 show that the preparation method of the present invention is superior to the known method X for the preparation of diethyl 1H-imidazole-4,5-dicarboxylate from diethyl L-(+)-tartaric acid under non-shade conditions in terms of yield.