[CH3:1][CH:2]([CH3:20])[C:3]([NH:5][C:6]1[CH:16]=[CH:15][C:9]([C:10]([O:12][CH2:13][CH3:14])=[O:11])=[CH:8][C:7]=1[N+:17]([O-])=O)=[O:4].CCCCCC.C(OCC)(=O)C>C(O)C.[Pt]=O>[NH2:17][C:7]1[CH:8]=[C:9]([CH:15]=[CH:16][C:6]=1[NH:5][C:3](=[O:4])[CH:2]([CH3:20])[CH3:1])[C:10]([O:12][CH2:13][CH3:14])=[O:11]A sample of ethyl 4-(2-methylpropionylamino)-3-nitrobenzoate (8.0 g, 0.0286 mol) was suspended in ethanol (75 mL) containing platinum oxide (50 mg). The reaction mixture was hydrogenated for 2 h at 35 psi. Thin-layer chromatographic analysis (SiO2, 1:1 hexane:ethyl acetate) showed disappearance of starting material along with the formation of a new lower-running spot (Rf =0.2). The mixture was then filtered through a pad of Celite and the pad washed with fresh ethanol. The filtrate was concentrated and the residue recrystallized from ethyl acetate-hexane. The solid was collected by filtration to give 5.0 g (70%) of ethyl 3-amino-4-(2-methylpropionylamino)benzoate. An analytical sample was prepared by recrystallization twice from ethyl acetate-hexane. The residue was collected by filtration and then dried in vacuo at acetone reflux to give a beige solid, mp 147°-149° C.
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