Under argon and at 0° C., 707 mg (50% strength in ethyl acetate, 1.11 mmol) of T3P and 0.29 ml (1.67 mmol) of N,N-diisopropylethylamine were added to a solution of 470 mg (purity 50%, 0.56 mmol) of 2-{4-[5-chloro-2-(trifluoromethyl)phenyl]-2-oxopyridin-1(2H)-yl}-3-(pyridin-2-yl)propanoic acid (racemate) and 129 mg (0.67 mmol) of tert-butyl 4-aminobenzoate in 45 ml of ethyl acetate. The reaction mixture was stirred at 60° C. for 1 h, another 353 mg (50% strength in ethyl acetate, 0.56 mmol) of T3P and 0.1 ml (0.56 mmol) of N,N-diisopropylethylamine were added and the mixture was stirred at 60° C. for 1 h. After addition of water/ethyl acetate and phase separation, the aqueous phase was extracted three times with ethyl acetate. The combined organic phases were dried (sodium sulphate), filtered and concentrated under reduced pressure. The crude product was purified by flash chromatography (silica gel 60, dichloromethane/methanol mixtures). Yield: 163 mg (purity 93%, 46% of theory)
