To a solution of 5-bromo-2-(trifluoromethyl)benzoic acid (1.0 g, 3.53 mmol) in CH2Cl2 (6 ml) at room temperature are added methyl 3-amino-3,5-dimethylbenzoate (0.44 g, 2.47 mmol, see preparation 12) and trimethylamine (1.0 ml, 7.06 mmol). After stirring the reaction mixture for 10 minutes, 1-propanephosphonic acid cyclic anhydride (50% solution in ethyl acetate, 5.6 ml, 8.83 mmol) is added via syringe. After 14 hours at ambient temperature, the reaction mixture is diluted with CH2Cl2, washed with water and brine. The organic layers are combined and dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure. The resulting residue is purified by flash chromatography (silica gel) using 20% ethyl acetate in hexanes to give the title compound as a white solid (0.6 g, 39%).
