Cl[C:2]1[C:3]([N+:11]([O-:13])=[O:12])=[C:4]([CH:8]=[CH:9][CH:10]=1)[C:5]([OH:7])=[O:6].[OH-].[K+].Cl.C(O)(C(F)(F)F)=[O:18]>O.O.CO>[OH:18][C:2]1[C:3]([N+:11]([O-:13])=[O:12])=[C:4]([CH:8]=[CH:9][CH:10]=1)[C:5]([OH:7])=[O:6]To a 250 mL flask were added 3-chloro-2-nitrobenzoic acid (10 g, 49.6 mmol) and a potassium hydroxide solution (40 g, 727 mmol) in water (70 mL). The thick slurry was heated to reflux for 12 hours. The solution was cooled in ice and cautiously brought to pH 3 with concentrated HCl. The aqueous mixture was extracted with EtOAc (3×). The organic layers were combined, washed with brine, dried with sodium sulfate and concentrated in vacuo. The crude product mixture was dissolved in dichloromethane and the resulting yellow precipitate was filtered to afford Intermediate A-15A (6 g, 32.8 mmol, 66.0% yield). HPLC: RT=0.85 min (H2O/MeOH with TFA, Sunfire C18 3.5 μm, 2.1×30 mm, gradient=4 min, wavelength=220 nm); MS(ES): m/z=206 [M+Na]+; 1H NMR (400 MHz, chloroform-d) δ 7.56-7.35 (m, 1H), 7.23 (dd, J=7.9, 1.5 Hz, 1H).
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