[CH3:1][O:2][C:3](=[O:14])[C:4]1[CH:9]=[C:8]([O:10][CH2:11][CH3:12])[CH:7]=[C:6]([NH2:13])[CH:5]=1.N1C=CC=CC=1.[Cl:21][CH2:22][CH2:23][CH2:24][S:25](Cl)(=[O:27])=[O:26]>C(Cl)Cl.CN(C1C=CN=CC=1)C>[CH3:1][O:2][C:3](=[O:14])[C:4]1[CH:9]=[C:8]([O:10][CH2:11][CH3:12])[CH:7]=[C:6]([NH:13][S:25]([CH2:24][CH2:23][CH2:22][Cl:21])(=[O:27])=[O:26])[CH:5]=1A suspension of 3-amino-5-ethoxy-benzoic acid methyl ester (D49) (4.0 g, 20.5 mmol, 1 equiv) in CH2Cl2 (100 ml) was treated with DMAP (400 mg, 3.2 mmol,) and pyridine (1.74 g, 22 mmol, 1.1 equiv) followed by 3-chloropropanesulfonyl chloride (3.89 g, 22 mmol, 1.1 equiv) dropwise. The resulting mixture was stirred for 16 h then concentrated in vacuo. The residue was dissolved in AcOEt (200 ml) and the resulting solution was washed with 2N aqueous HCl solution (100 ml) followed by saturated aqueous NaHCO3 solution (100 ml), then dried over MgSO4 and concentrated in vacuo to give 3-(3-chloro-propane-1-sulfonylamino)-5-ethoxy-benzoic acid methyl ester (D53) (6.7 g, 98%) as a pale orange solid.
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