[CH2:1]([CH:3]([C:9](=O)[CH3:10])[C:4]([O:6][CH2:7][CH3:8])=[O:5])[CH3:2].C([O-])(=O)C.[NH4+:16].N.S([O-])([O-])(=O)=O.[Na+].[Na+]>CO>[NH2:16]/[C:9](/[CH3:10])=[C:3](/[CH2:1][CH3:2])\[C:4]([O:6][CH2:7][CH3:8])=[O:5]A 100-mL round bottom flask was charged with ethyl 2-ethyl-3-oxo-butanoate (5 g, 90% purity, 28 mmol), ammonium acetate (22 g, 280 mmol, 10 eq.), ammonia (2N in EtOH, 14 ml, 1 eq.), anhydrous sodium sulfate (8 g, 56 mmol, 2 eq.) and MeOH (30 ml). The resulting mixture was stirred at room temperature overnight. The volatile material was removed under reduced pressure and the residue was treated with dichloromethane (40 ml). Insoluble material was removed by filtration and washed with dichloromethane (2×20 ml). The organics was washed with aqueous sodium bicarbonate, dried over Na2SO4. Removal of solvent gave ethyl (Z)-3-amino-2-ethyl-but-2-enoate (4.1 g, 82% yield) as a white solid.
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