[Br:1][C:2]1[CH:8]=[CH:7][CH:6]=[CH:5][C:3]=1[NH2:4].N([O-])=[O:10].[Na+].[C:13]([O-])(=O)[CH3:14].[Na+].[CH2:18]([O:20][C:21]([CH:23]1[CH2:27][CH2:26][CH2:25][C:24]1=[O:28])=[O:22])[CH3:19]>Cl.O>[Br:1][C:2]1[CH:8]=[CH:7][CH:6]=[C:5]2[C:3]=1[NH:4][C:25]([C:24]([O:28][CH2:13][CH3:14])=[O:10])=[C:26]2[CH2:27][CH2:23][C:21]([O:20][CH2:18][CH3:19])=[O:22]
A mixture of 2-bromoaniline (34.2 g) in 5M HCl (50 mL) and water (250 mL) at 0° C. was treated with NaNO2 (13.8 g) in water (200 mL). After addition, sodium acetate (92.3 g) in water (250 mL) and 2-oxo-cyclopentanecarboxylic acid ethyl ester (30 mL) were added. The mixture was stirred for 15 minutes, warmed to 19° C. over two hours and extracted with dichloromethane. The extract was dried (MgSO4), filtered and concentrated. The concentrate was dissolved in 1.1:1 H2SO4:ethanol (30 mL), refluxed overnight, cooled to room temperature, quenched with water (1.5 L), and filtered. The filtrant was dissolved in dichloromethane (200 mL) and filtered through a Flash 75 cartridge with dichloromethane. After concentration, the product was recrystallized from hexane.
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