Dimethylformamide → 2-Methyl hydrogen 2,3-dihydro-3-hydroxythiazolo[3,2-a]benzoimidazole-2,7-dicarboxylate

Participants

Reaction Conditions

Reaction Steps

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).

Provenance & Evidence