反应详情

温度

60 °C

Methyl 2-chloro-3-hydroxypropenoate (114 g) was added to DMF (460 ml) solution of 2-mercaptobenzoimidazole-5-carboxylic acid (135 g), and the mixture was stirred overnight at 60° C. After cooling to room temperature, water (3 L) was gradually added to the reaction solution and stirred. The thus precipitated crystals were collected by filtration to obtain crude crystals of 2-methyl hydrogen 2,3-dihydro-3-hydroxythiazolo[3,2-a]benzoimidazole-2,7-dicarboxylate (168 g). Next, the thus obtained crude crystals were suspended in 1,4-dioxane (1.5 L), and the suspension was mixed with 4 M HCl 1,4-dioxane solution (500 ml) and stirred at room temperature for 60 hours. The resulting precipitate was collected by filtration and washed with 1,4-dioxane to obtain crude crystals of 2-methyl hydrogen 2,3-dihydro-3-hydroxythiazolo[3,2-a]benzoimidazole-2,6-dicarboxylate hydrochloride (189 g). The thus obtained crude crystals were slowly added to concentrated sulfuric acid (750 ml) which was heated at 60° C. and stirred at the same temperature for 1 hour. After cooling to room temperature, the reaction solution was poured into ice water, and the thus precipitated crystals were collected by filtration to obtain the title compound (152 g).

1. temperatureAfter cooling to room temperature
2. stirringstirred
3. filtrationThe thus precipitated crystals were collected by filtration