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

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

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%.

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