[F:1][C:2]([F:13])([F:12])[C:3]([C:6]1[O:10][N:9]=[C:8]([NH2:11])[CH:7]=1)([CH3:5])[CH3:4].C(=O)([O-])[O-].[K+].[K+].Cl[C:21]([O:23][C:24]1[CH:29]=[CH:28][C:27]([Cl:30])=[CH:26][CH:25]=1)=[O:22]>C1COCC1>[F:13][C:2]([F:1])([F:12])[C:3]([C:6]1[O:10][N:9]=[C:8]([NH:11][C:21](=[O:22])[O:23][C:24]2[CH:29]=[CH:28][C:27]([Cl:30])=[CH:26][CH:25]=2)[CH:7]=1)([CH3:5])[CH3:4]5-(1,1,1-trifluoro-2-methylpropan-2-yl)isoxazol-3-amine (123 mg, 0.63 mmol) in THF (2 mL) was treated with potassium carbonate (113 mg, 0.819 mmol) and p-chlorophenyl chloroformate (180 mg, 0.95 mmol). The reaction mixture was stirred at rt overnight. The mixture was filtered through a celite pad, washed with ethyl acetate and concentrated to dryness. The residue was taken into ethyl acetate, washed with brine, and the organics dried (MgSO4) and concentrated. The residue was purified by silica gel chromatography (hexane/ethyl acetate 8:2) to give 4-chlorophenyl 5-(1,1,1-trifluoro-2-methylpropan-2-yl)isoxazol-3-ylcarbamate (85 mg, 39%) as a white solid. 1H NMR (300 MHz, CDCl3) δ 7.83 (brs, 1H), 7.38 (d, J=9 Hz, 2H), 7.15 (d, J=9 Hz, 2H), 6.82 (s, 1H), 1.59 (s, 6H); LC-MS (ESI) m/z 349 (M+H)+.
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