Potassium Carbonate → Indoline-2-carboxylic acid, (S)-

Temperature

95 °C

A flask was charged successively with 3.00 g (15.0 mmol) (S)-2-amino-3-(2-chloro-phenyl)-propionic acid, 2.17 g (15.7 mmol) K2CO3, 15 mg CuCl (2.9 mmol) and 15 g H2O. The reactor was flushed with argon and then kept under a slow stream of argon. The reaction mixture was stirred and heated until 95° C. and kept at this temperature for 22 h. Samples were taken regularly and analyzed by HPLC. The conversion after 22 h was approximately 40%. Then 15 mL water was added and the mixture stirred and heated for an additional 18 h. HPLC indicated full conversion of (S)-2-chlorophenylalanine. The reaction mixture was cooled to ca 25° C. The pH of the solution was then decreased from 7.6 to ca 3.5. The precipitated (S)-2,3-dihydro-1H-indole-2-carboxylic acid was isolated by filtration and washed with 2×10 mL 0.01 M HCl. Found after drying 1.88 g (11.5 mmol) (S)-2,3-dihydro-1H-indole-2-carboxylic acid. Yield 76.6%, ee>99%.

1. customThe reactor was flushed with argon
2. waitThe conversion after 22 h was
3. additionThen 15 mL water was added
4. stirringthe mixture stirred
5. temperatureheated for an additional 18 h
6. temperatureThe reaction mixture was cooled to ca 25° C

ORD record

ord-ec40443ad3ee4ce8b646223e5248710a

Source dataset

uspto-grants-2010_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07732621B2