N1CCC[C@H]1C(O)=O.[BH4-].[Na+].[N+:11]([C:14]1[CH:19]=[CH:18][CH:17]=[CH:16][C:15]=1[CH2:20][C:21](=[O:25])[C:22]([OH:24])=[O:23])([O-:13])=[O:12]>O1CCCC1>[OH:25][CH:21]([CH2:20][C:15]1[CH:16]=[CH:17][CH:18]=[CH:19][C:14]=1[N+:11]([O-:13])=[O:12])[C:22]([OH:24])=[O:23]L-(-)-proline (7.50 g., 65.1 mmol) and sodium borohydride (2.46 g., 65.1 mmol) were stirred in tetrahydrofuran under nitrogen for sixteen hours. Recrystallized o-nitrophenylpyruvic acid (14.17 g., 76.5 mmol) in tetrahydrofuran (50 ml.) was added dropwise, and the resulting solution was stirred at room temperature for six days. The solvent was evaporated and the resulting gum was stirred with 10% aqueous HCl (200 ml.) for 4.5 hours. A small amount of solid was filtered to provide nearly racemic α-hydroxy-2-nitrobenzenepropanoic acid, 1.25 g., m.p. 98°-102° C., [α]D25 -4.21° (c 2.045, EtOH).
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