合成路线1

5-Formyl-2-methoxybenzoic acid (I) is converted to the corresponding benzyl ester (II) upon treatment with benzyl bromide and potassium bicarbonate. Subsequent Wadsworth-Emmons condensation between aldehyde (II) and triethyl 2-phosphonobutyrate (III) gives the unsaturated ester (IV). Double bond hydrogenation in (IV) with concomitant hydrogenolysis of the benzyl ester affords acid (V), which is subsequently coupled with 4-(trifluoromethyl)benzyl amine (VI), via the mixed anhydride with ethyl chloroformate, to produce amide (VII). The ethyl ester group of (VII) is finally hydrolyzed to the title carboxylic acid employing NaOH in aqueous ethanol.