Methanol → 5,5,5-Trifluoro-2-methoxy-carbonylamino-pentanoic acid

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Reaction Steps

To a solution of 5,5,5-Trifluoro-2-methoxycarbonylamino-pentanoic acid methyl ester (194 mg, 0.80 mmol) in methanol (3 mL) was added an aqueous LiOH solution (1M, 2 mL, 2 mmol). The resulting solution was stirred at room temperature for 45 minutes and then washed with ethyl acetate. The ethyl acetate washing was discarded and the aqueous layer was acidified with concentrated HCl. The acidified aqueous layer was extracted twice with ethyl acetate. The combined organics were washed with brine, dried (MgSO4), and concentrated to give clean 5,5,5-Trifluoro-2-methoxy-carbonylamino-pentanoic acid. To a solution of the pentanoic acid in dimethylformamide (2 mL) was added HATU (300 mg, 0.79 mmol). After stirring for 5 minutes, a solution of 2-{5-[4′-(2-pyrrolidin-2-yl-3H-imidazol-4-yl)-biphenyl-4-yl]-1H-imidazol-2-yl}-pyrrolidine-1-carboxylic acid tert-butyl ester (412 mg, 0.79 mmol) in dimethylformamide (1.9 mL) was added to the reaction, followed immediately by diisopropylethylamine (275 μL, 1.58 mmol). The reaction was stirred for 1 hour at room temperature then diluted with ethyl acetate. The organic layer was washed with water and brine, dried (MgSO4), concentrated and purified by flash chromatography to yield 2-[5-(4′-{2-[1-(5,5,5-trifluoro-2-methoxycarbonylamino-pentanoyl)-pyrrolidin-2-yl]-3H-imidazol-4-yl}-biphenyl-4-yl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester (340 mg, 59%). LCMS-ESI+: calculated for C38H44F3N7O5: 735.34; observed [M+1]+: 736.05.

Provenance & Evidence