3-(3-Trifluoromethylphenyl)-2-(4-trifluoromethylphenyl)-propionic acid (105, 2.43 g, crude) was dissolved in anhydrous THF (6 mL) at ambient temperature. CDI (1.64 g, 10.1 mmol) was charged as a solid, followed by EtOAc (4 mL), to rinse the vial. The internal temperature remained between 20-21° C. during the addition. N-acetylethanolamine (3.6 mL, 39 mmol) was added, whereupon the temperature rose to 24.5° C. The mixture was stirred overnight (16 h) at 23-24° C. and then rotary evaporated to a gummy residue. This was chromatographed on silica gel using EtOAc: hexane (70:30 v/v) (Rf=0.35-0.40) to afford 2-acetamidoethyl-3-(3-trifluoromethylphenyl)-2-(4-trifluoromethylphenyl)propionate 105A (1.85 g).
