[Cl:1][C:2]1[CH:8]=[CH:7][C:5]([NH2:6])=[C:4]([F:9])[CH:3]=1.[C:10]1(=O)[O:15][C:13](=[O:14])[C:12]2[CH2:16][CH2:17][CH2:18][CH2:19][C:11]1=2.O.C(OCC)(=O)C.C(OCC)(=O)C>C(O)(=O)C>[Cl:1][C:2]1[CH:8]=[CH:7][C:5]([N:6]2[C:10](=[O:15])[C:11]3[CH2:19][CH2:18][CH2:17][CH2:16][C:12]=3[C:13]2=[O:14])=[C:4]([F:9])[CH:3]=1
A mixture of 4-chloro-2-fluoroaniline (19.0 g, 130.6 mmol), and 3,4,5,6-tetrahydrophthalic anhydride (19.85 g, 130.6 mmol) in acetic acid (150 mL) is refluxed for 2 hours, treated with additional 4-chloro-2-fluoroaniline (3.0 g), refluxed for 90 minutes, stirred at room temperature overnight and poured into a water/ethyl acetate mixture. The organic phase is washed sequentially with water, saturated sodium hydrogen carbonate solution and brine, dried over anhydrous magnesium sulfate and concentrated in vacuo to obtain a purple oil. Flash column chromatography of the oil using silica gel and 15% to 20% ethyl acetate in hexanes solutions gives the title product as an off-white solid (25.3 g, mp 81°-82° C.).
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