[C:1](=[O:4])([O-])[O-:2].[Cs+].[Cs+].[CH3:7]N(C)C=O.C(OC(=O)N[CH:19]([C:24]1[CH:28]=[C:27]([CH2:29]Br)ON=1)CC(C)C)(C)(C)C.[CH2:32]([CH:34]([CH2:45]C)[C:35](NC(C([O-])=O)C([O-])=O)=O)[CH3:33].[CH2:47]([O:49][CH2:50][CH3:51])[CH3:48]>>[CH3:7][O:2][C:1](=[O:4])[CH2:45][C:34]1[CH:32]=[CH:33][C:47]([O:49][CH2:50][C:51]2[CH:19]=[CH:24][CH:28]=[CH:27][CH:29]=2)=[CH:48][CH:35]=1Cesium carbonate (18.28 g, 56.1 mmol, 3.0 equivalents) was added to a dimethyl formamide (300 mL) solution of [1-(5-bromomethyl-isoxazol-3-yl)-3-methyl-butyl]-carbamic acid tert-butyl ester (6.48 g, 18.7 mmol, 1.00 equivalents) and diethylacetamidomalonate (4.86 g, 22.4 mmol, 1.20 equivalents) at 0° C. The mixture was stirred at room temperature for 5 hours. The reaction was poured into diethyl ether (200 mL) and extracted with water (5×200 mL) and brine (200 mL). The organic portion was dried over sodium sulfate and the solvent was removed in vacuo to give the title compound as a viscous oil (8.99 g, 99.4%). MS (Cl) m/z 484.0 (M+1), 384.1 (M−99). H. [1-(5-Bromomethyl-isoxazol-3-yl)-3-methyl-butyl]-carbamic acid t-butyl ester
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