Hydrochloric Acid → (S)-Indoline-2-carboxylic acid ethyl ester
Reaction equation
Cl.[NH:2]1[C:10]2[C:5](=[CH:6][CH:7]=[CH:8][CH:9]=2)[CH2:4][C@H:3]1[C:11]([OH:13])=[O:12].[CH2:14](O)[CH3:15]>>[CH2:14]([O:12][C:11]([C@@H:3]1[CH2:4][C:5]2[C:10](=[CH:9][CH:8]=[CH:7][CH:6]=2)[NH:2]1)=[O:13])[CH3:15]Participants
4
Procedure
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%).