[F:1][C:2]1[CH:3]=[C:4]([CH3:14])[C:5]([N+:11]([O-:13])=[O:12])=[C:6]([CH:10]=1)[C:7]([OH:9])=[O:8].[C:15](=O)([O-])[O-].[Cs+].[Cs+].IC>CN(C=O)C.O>[F:1][C:2]1[CH:3]=[C:4]([CH3:14])[C:5]([N+:11]([O-:13])=[O:12])=[C:6]([CH:10]=1)[C:7]([O:9][CH3:15])=[O:8]To a solution of 5-fluoro-3-methyl-2-nitrobenzoic acid (8.0 g, 40 mmol) from Step A above in DMF (100 mL) was added cesium carbonate (20.0 g, 60 mmol) followed by iodomethane (3.0 ml, 48 mmol). The reaction solution was stirred at ambient temperature overnight. The reaction mixture was diluted with water and extracted with ethyl acetate. The organic extract was separated, washed with brine, dried (Na2SO4), and concentrated in vacuo to afford methyl 5-fluoro-3-methyl-2-nitrobenzoate (8.4 g, 98%) as a yellow solid: 1H NMR (500 MHz, DMSO-d6) δ 7.71-7.67 (m, 2H), 3.85 (s, 3H), 2.32 (s, 3H); MS (ESI+) m/z 214 (M+H).
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