[NH2:1][CH:2]([C:7]1[CH:12]=[CH:11][C:10]([N+]([O-])=O)=[CH:9][C:8]=1[CH3:16])[CH2:3][C:4]([OH:6])=[O:5].CC1C=C([N+:26]([O-:28])=[O:27])C=CC=1C=O.C(O)(=O)CC(O)=O.C([O-])(=O)C.[NH4+]>C(O)C>[NH2:1][CH:2]([C:7]1[CH:12]=[C:11]([N+:26]([O-:28])=[O:27])[CH:10]=[CH:9][C:8]=1[CH3:16])[CH2:3][C:4]([OH:6])=[O:5]
Following the General Procedure of Description 3, 3-amino-3-(2-methyl-4-nitro-phenyl)propanoic acid (2c) was prepared from 2-methyl-4-nitro-benzaldehyde (2b) (800 mg, 5.0 mmol), malonic acid (520 mg, 5.0 mmol), and ammonium acetate (NH4OAc) (578 mg, 7.5 mmol) in ethanol (EtOH) (10 mL) at reflux for 48 h (oil bath). The reaction was followed by LC/MS to completion. Filtrative work-up afforded 510 mg (45% yield) of the target compound (1c) as a near colorless solid which was of sufficient purity to be used directly in the next step without further purification and isolation. 1H NMR (300 MHz, D2O): δ 8.01-7.97 (m, 2H), 7.46 (d, J=8.4 Hz, 1H), 4.83 (t, J=7.2 Hz, 1H), 2.70-2.65 (m, 2H), 2.33 (s, 3H) ppm. LC/MS: Rt=1.274 min; ESI (pos.) m/z=225.1 (M+H+)+.
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