[Br:1][C:2]1[CH:3]=[C:4]([CH:8]=[C:9]([N+:11]([O-:13])=[O:12])[CH:10]=1)[C:5]([OH:7])=[O:6].O=S(Cl)Cl.[CH3:18]O>>[CH3:18][O:6][C:5](=[O:7])[C:4]1[CH:8]=[C:9]([N+:11]([O-:13])=[O:12])[CH:10]=[C:2]([Br:1])[CH:3]=1To a solution of 3-bromo-5-nitro-benzoic acid (D5) (22.3 g, 90.6 mmol, 1 equiv) in MeOH (300 ml) at 0° C. was added SOCl2 (7.9 ml, 108 mmol, 1.2 equiv) dropwise. The resulting solution was stirred at reflux for 4 hours then cooled to room temperature and concentrated in vacuo. The residue was diluted with AcOEt, washed twice with 2N aqueous NaOH solution and once with brine, dried over MgSO4 and concentrated in vacuo to give 3-bromo-5-nitro-benzoic acid methyl ester (D11) (22.1 g, 94%) as a pale brown solid. RT=3.18 min
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