反应详情

85% phosphoric acid (0.23 mL, 1.96 mmol) was added to a solution of ethyl 2-{3-[(tert-butoxycarbonyl)amino]azetidin-1-yl)-1,3-benzothiazole-6-carboxylate obtained in Example (225b) (296 mg, 0.78 mmol) in dichloromethane (2 mL) at room temperature, followed by stirring for 27 hours. Then, THF (1 mL) and 85% phosphoric acid (0.23 mL, 1.96 mmol) were added, and the mixture was further stirred for five hours. Water was added to the reaction solution, and the mixture was washed with ethyl acetate. Then, a 1 N aqueous sodium hydroxide solution was added to the aqueous layer, followed by extraction with a chloroform/methanol mixed solvent. The combined organic layers were dried over anhydrous magnesium sulfate and filtered. Thereafter, the solvent was evaporated under reduced pressure to obtain 190 mg of the title compound as a milk white solid (87%).

1. stirringthe mixture was further stirred for five hours
2. washthe mixture was washed with ethyl acetate
3. additionThen, a 1 N aqueous sodium hydroxide solution was added to the aqueous layer
4. extractionfollowed by extraction with a chloroform/methanol mixed solvent
5. dry with materialThe combined organic layers were dried over anhydrous magnesium sulfate
6. filtrationfiltered
7. customThereafter, the solvent was evaporated under reduced pressure