Diisopropylethylamine → Methyl 4-[(5-bromo-2-fluoro-benzoyl)amino]-3,5-dimethyl-benzoate

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Reaction Steps

To a solution of 5-bromo-2-fluorobenzoic acid (3.50 g, 15.9 mmol) in CH2Cl2 (50 mL) at 0° C. are added methyl 4-amino-3,5-dimethylbenzoate (2.86 g, 15.9 mmol, see preparation 12) and N,N-diisopropylethylamine (8.35 ml, 47.9 mmol). After stirring the reaction mixture for 10 minutes, 1-propanephosphonic acid cyclic anhydride (50% solution in ethyl acetate, 20.5 ml, 31.9 mmol) is added via syringe and stirred at ambient temperature. After 36 hours, the solvent is removed under reduced pressure and the residue is diluted with water and extracted with ethyl acetate. 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 10% ethyl acetate in hexane to give the title compound as a white solid (4.20 g, 69%). Mass spectrum (m/z): 380.2 (M+1).

Provenance & Evidence