[Cl:1][C:2]1[C:3]([N+:12]([O-:14])=[O:13])=[CH:4][C:5]([CH3:11])=[C:6]([CH:10]=1)[C:7]([OH:9])=[O:8].S(Cl)(Cl)=O.[CH3:19]O>>[Cl:1][C:2]1[C:3]([N+:12]([O-:14])=[O:13])=[CH:4][C:5]([CH3:11])=[C:6]([CH:10]=1)[C:7]([O:9][CH3:19])=[O:8]To 5-chloro-2-methyl-4-nitrobenzoic acid (900 mg, 4.15 mmol) in methanol (10 mL) was added thionyl chloride (0.3 mL, 4.15 mmol) dropwise. The mixture was heated to reflux for 5 h and then allowed to cool. The solvent was removed in vacuo and the residue was partitioned between DCM (20 mL) and saturated aqueous NaHCO3 (20 mL). The organic phase was passed through a hydrophobic frit and the solvent was removed in vacuo to give methyl 5-chloro-2-methyl-4-nitrobenzoate (880 mg, 92%) as an off-white solid. LCMS (10 cm_ESCI_Formic_MeCN): [M+H]+=230 at 4.25 min. 1H NMR (400 MHz, CDCl3): δ 8.08 (s, 1H), 7.73 (s, 1H), 3.95 (s, 3H), 2.64 (s, 3H).
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