反应详情

HCl gas was bubbled through a stirring suspension of (S)-indoline-2-carboxylic acid (20 g, 110 mmol) in ethanol (500 mL). When the acid was completely dissolved, the solution was brought to reflux. After 16 hours, the solution was cooled and the solvent removed in vacuo. The residue was triturated with diethyl ether and the resulting off-white solid was collected by filtration, washed with hexanes and dried overnight in a vacuum oven at 30° C. to give (S)-indoline-2-carboxylic acid ethyl ester.HCl (25.7 g, 78%).

1. dissolutionWhen the acid was completely dissolved
2. temperatureto reflux
3. temperaturethe solution was cooled
4. customthe solvent removed in vacuo
5. customThe residue was triturated with diethyl ether
6. filtrationthe resulting off-white solid was collected by filtration
7. washwashed with hexanes
8. customdried overnight in a vacuum oven at 30° C.