N[C@H:2]([C:10]([OH:12])=[O:11])[CH2:3][C:4]1[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=1.S(=O)(=O)(O)[OH:14].N([O-])=O.[Na+]>O>[OH:14][C@@H:2]([CH2:3][C:4]1[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=1)[C:10]([OH:12])=[O:11]L-Phenylalanine (10.00 g, 60.5 mmol) was added to a dilution of 4.15 g (42.4 mmol) of concentrated sulfuric acid in 110 g of water and then, at an inside temperature of 20° C., a mixture of 10.45 g (151.5 mmol) of sodium nitrite and 20 g of water was added over 5 hours. After addition, the mixture was further stirred at 20° C. for 20 hours and, thereafter, the same work-up procedure as in Example 1 was followed. The combined extract (115.8 g) obtained contained 8.7 g of (2S)-2-hydroxy-3-phenylpropionic acid (yield 87%, optical purity 92.0% ee). The proton concentration (normality) in the reaction of this example was 0.8 mol/kg, the amount of the protonic acid was 1.4 equivalents (relative to L-phenylalanine), and the reaction temperature was 20° C.
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