[Br:1][C:2]1[CH:7]=[C:6]([N+:8]([O-:10])=[O:9])[C:5]([NH:11]C(=O)C(F)(F)F)=[C:4]([CH:18]2[CH2:22][CH2:21][CH2:20][O:19]2)[C:3]=1[F:23].O1CCOCC1.S(=O)(=O)(O)O.C([O-])(O)=O.[Na+]>CCOC(C)=O>[Br:1][C:2]1[CH:7]=[C:6]([N+:8]([O-:10])=[O:9])[C:5]([NH2:11])=[C:4]([CH:18]2[CH2:22][CH2:21][CH2:20][O:19]2)[C:3]=1[F:23]
A reaction flask was charged with N-(4-bromo-3-fluoro-6-nitro-2-tetrahydrofuran-2-yl-phenyl)-2,2,2-trifluoro-acetamide (18) (242.3 g, 604.1 mmol), 1,4-dioxane (1.212 L), and aqueous 2 M sulfuric acid (362.4 mL, 724.9 mmol), and stirred at reflux for 5 days (HPLC showed 98% conversion). The reaction mixture was allowed to cool, diluted with EtOAc, neutralized with saturated aqueous NaHCO3, separated the layers, and re-extracted the aqueous phase with EtOAc (2×). The combined organic phase was washed with brine (2×), dried over MgSO4, filtered and concentrated in vacuo giving 19 as a greenish brown solid (181.7 g, 94% yield; 95% HPLC purity). The product was carried to the next step without further purification. LCMS (C18 column eluting with 10-90% CH3CN/water gradient over 5 minutes with formic acid modifier) M+1: 305.20 (3.63 min). 1H NMR (300 MHz, CDCl3) δ 8.35 (d, J=7.3 Hz, 1H), 7.45 (s, 2H), 5.23-5.16 (m, 1H), 4.23-4.14 (m, 1H), 3.93-3.84 (m, 1H), 2.31-1.96 (m, 4H) ppm.
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