[CH3:1][O:2][C:3]1[CH:10]=[C:9]([O:11][CH3:12])[CH:8]=[CH:7][C:4]=1[CH:5]=O.[C:13]([OH:19])(=[O:18])[CH2:14]C(O)=O.C([O-])(=O)C.[NH4+:24]>C(O)C>[NH2:24][CH:5]([C:4]1[CH:7]=[CH:8][C:9]([O:11][CH3:12])=[CH:10][C:3]=1[O:2][CH3:1])[CH2:14][C:13]([OH:19])=[O:18]A mixture of 2,4-dimethoxybenzaldehyde (21 g, 0.126 mol), malonic acid (20 g, 0.192 mol), ammonium acetate (30 g, 0.39 mol) and ethanol (40 ml) was stirred and heated on a water bath. After refluxing for 4 h the mixture was cooled to 40° C. and the precipitated salt was filtered off and washed with cold ethanol (40 ml). By additional cooling on ice a further crystalline material precipitated, which was isolated and washed with cold ethanol (40 ml) and ether (40 ml). Recrystallisation from ethanol/water 60:40 gave 3-amino-3-(2,4-dimethoxyphenyl)propanoic acid (10.3 g, 38%).
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