[C:1]([NH:11][C@H:12]([C:15]([OH:17])=[O:16])[CH2:13]Cl)([O:3][CH2:4][C:5]1[CH:10]=[CH:9][CH:8]=[CH:7][CH:6]=1)=[O:2].[OH-].[Na+].[C:20]1([SH:26])[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=1.Cl>O>[C:1]([NH:11][C@H:12]([C:15]([OH:17])=[O:16])[CH2:13][S:26][C:20]1[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=1)([O:3][CH2:4][C:5]1[CH:10]=[CH:9][CH:8]=[CH:7][CH:6]=1)=[O:2]N-Carbobenzyloxy-β-chloro-L-alanine (0.137 g, 0.53 mmol) was dissolved in 0.68 ml of water and, then, 0.58 ml of 2 N aqueous sodium hydroxide was added. Thereafter, 0.069 g (0.63 mmol) of thiophenol was added dropwise at room temperature in a nitrogen gas atmosphere. After 2 hours of stirring at 60° C., the reaction mixture was cooled with ice and acidified with 1 N hydrochloric acid, and then extracted with ethyl acetate. The solvent was distilled off and the residue was purified by column chromatography to give 0.107 g (0.32 mmol, 61%) of N-carbobenzyloxy-S-phenyl-L-cysteine. The product obtained had an optical purity of not less than 98% e.e. as determined by HPLC analysis in the same manner as in Example 13.
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