[Na].[C:2]([NH:5][CH:6]([C:12]([O:14][CH2:15][CH3:16])=[O:13])[C:7]([O:9][CH2:10][CH3:11])=[O:8])(=[O:4])[CH3:3].Br[CH2:18]/[CH:19]=[CH:20]/[CH3:21]>C(O)C>[C:2]([NH:5][C:6]([CH2:18]/[CH:19]=[CH:20]/[CH3:21])([C:12]([O:14][CH2:15][CH3:16])=[O:13])[C:7]([O:9][CH2:10][CH3:11])=[O:8])(=[O:4])[CH3:3]3.86 g (168 mmol) of sodium metal were dissolved in 106 ml of anhydrous ethanol. 36.35 g (168 mmol) of diethyl acetamidomalonate dissolved in 225 ml of anhydrous ethanol were added and the mixture was heated under reflux for 10 minutes. 22.66 g (168 mmol) of (E)-1-bromo-2-butene were added dropwise at room temperature and the mixture was stirred overnight and then evaporated to dryness under a vacuum. The residue was partitioned between ethyl acetate and 0.1M hydrochloric acid. The organic phase was washed with saturated sodium hydrogen carbonate solution and then with saturated sodium chloride solution and dried over anhydrous magnesium sulphate. The solvent was evaporated to give 40 g of diethyl (E)-2-acetamido-2-(2-butenyl)malonate as a colourless oil; 1H NMR (250 MHz, CDCl3) d: 1.25 (t, 6H), 1.6 (d, 3H), 2.0 (s, 3H), 2.9 (d, 2H), 4.2 (q, 4H), 5.15 (m, 1H) 5.5 (m, 1H), 6.7 s, 1H).
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