[Cl:1][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.C(Cl)(=O)C(Cl)=O.CN(C=O)C.[C:25]1([CH3:33])[CH:30]=[CH:29][CH:28]=[C:27]([Mg]Br)[CH:26]=1>O1CCCC1>[Cl:1][C:2]1[C:3]([N+:11]([O-:13])=[O:12])=[C:4]([C:5]([C:27]2[CH:26]=[C:25]([CH3:33])[CH:30]=[CH:29][CH:28]=2)=[O:7])[CH:8]=[CH:9][CH:10]=1
A solution of 3-chloro-2-nitrobenzoic acid (2.5 g, 12.40 mmol) in tetrahydrofuran (50 mL) was treated with oxalyl chloride (1.194 mL, 13.64 mmol) followed by DMF (0.096 mL, 1.240 mmol). The reaction mixture was stirred at room temperature for 2 hrs. After cooling to 0° C., a 1M solution of m-tolylmagnesium bromide (24.81 mL, 24.81 mmol) was added. After 1 hr another portion of m-tolylmagnesium bromide (24.81 mL, 24.81 mmol) was added. After 1 hour, the reaction mixture was partitioned between ethyl acetate (200 mL) and 1N HCl (150 mL). The aqueous layer was extracted with ethyl acetate (2×100 mL). The combined organic phases were dried over Na2SO4, filtered and concentrated. The crude material was purified by flash chromatography (Teledyne ISCO CombiFlash Rf, 0% to 100% solvent A/B=ethyl acetate/heptane, REDISEP® SiO2 120 g) to provided Intermediate A-18A (0.700 g, 21%). 1H NMR (400 MHz, DMSO-d6) δ 8.04 (dd, J=8.1, 1.1 Hz, 1H), 7.82 (t, J=7.9 Hz, 1H), 7.71 (dd, J=7.7, 1.1 Hz, 1H), 7.66-7.54 (m, 3H), 7.52-7.46 (m, 1H), 2.40 (s, 3H).
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