[C:1]([O:5][C:6](=[O:17])[C:7]1[CH:12]=[CH:11][C:10](Cl)=[C:9]([N+:14]([O-:16])=[O:15])[CH:8]=1)([CH3:4])([CH3:3])[CH3:2].[CH2:18]([NH2:20])[CH3:19].C1COCC1>C1COCC1>[C:1]([O:5][C:6](=[O:17])[C:7]1[CH:12]=[CH:11][C:10]([NH:20][CH2:18][CH3:19])=[C:9]([N+:14]([O-:16])=[O:15])[CH:8]=1)([CH3:4])([CH3:3])[CH3:2]4-Chloro-3-nitrobenzoic acid tert-butyl ester (3.0 g, 11.6 mmol), prepared according to a published procedure [WO 9707101], was cautiously added to a solution of 2.0 M EtNH2/THF (20 mL, 40 mmol) and TEA (2.0 mL, 14 mmol) in anhydrous THF (30 mL). The resulting mixture was heated at 65° C. for 3 h, cooled, concentrated under reduced pressure, diluted with DCM (200 mL), washed with water (2×100 mL) and brine (50 mL), dried over anhydrous Na2SO4 and concentrated to give the title compound (3.1 g, 99%) as a yellow solid, which was used without further purification. 1H-NMR (CDCl3): δ 8.80 (1H, d), 8.24 (1H, br s), 8.02 (1H, dd), 6.84 (1H, d), 3.41 (2H, m), 1.59 (9H, s), 1.40 (3H, t).
Wird geladen…