[NH2:1][C:2]1[CH:3]=[C:4]([CH:8]=[C:9]([C:11]([F:14])([F:13])[F:12])[CH:10]=1)[C:5]([OH:7])=[O:6].CO[CH:17]1[CH2:21][CH2:20][CH:19](OC)O1>C(O)(=O)C.O1CCOCC1>[N:1]1([C:2]2[CH:3]=[C:4]([CH:8]=[C:9]([C:11]([F:12])([F:13])[F:14])[CH:10]=2)[C:5]([OH:7])=[O:6])[CH:17]=[CH:21][CH:20]=[CH:19]1A solution of 3-amino-5-(trifluoromethyl)benzoic acid (2.0 g) and 2,5-dimethoxytetrahydrofuran (1.52 ml) in a mixture of acetic acid (10 ml) and 1,4-dioxane (10 ml) was stirred at 100° C. for 2 hours. After cooling to room temperature, the mixture was concentrated and purified with column chromatography (silica gel, 50 ml, methanol:dichloromethane=10:90) to give crude solid. The solid was recrystallized from ethyl acetate (5.0 ml) and hexane (200 ml) to give 3-(pyrrol-1-yl)-5-(trifluoromethyl)-benzoic acid (1.72 g) as a powder.
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