[NH2:1][C@@H:2]([CH2:6][C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][C:8]=1Cl)[C:3]([OH:5])=[O:4].C([O-])([O-])=O.[K+].[K+]>Cl[Cu].O>[NH:1]1[C:12]2[C:7](=[CH:8][CH:9]=[CH:10][CH:11]=2)[CH2:6][C@H:2]1[C:3]([OH:5])=[O:4]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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