Diisopropylethylamine → N-[(2-chloro-6-methylphenyl)carbonyl]-4-[1,6-dimethyl-4-(trifluoromethyl)-2-oxo-3-pyridinyl]-L-phenylalanine methyl ester

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Reaction Steps

To a suspension of 4-[1,6-dimethyl-4-(trifluoromethyl)-2-oxo-3-pyridinyl]-L-phenylalanine methyl ester hydrochloride salt (100 mg, 0.25 mmol), 2-chloro-6-methylbenzoic acid (60 mg, 0.35 mmol) and HBTU (132 mg, 0.35 mmol) in DMF (2 mL) was added DIEA (174 μL, 1.0 mmol) at room temperature. The resulting mixture was stirred for 72 h. Then, the mixture was poured into water (25 mL) and was extracted with ethyl acetate (2×15 mL). The combined ethyl acetate extracts were washed successively with 0.5 N HCl (25 mL), saturated NaHCO3 solution (25 mL), brine solution (25 mL) and were dried over anhydrous magnesium sulfate. Filtration of the drying agent and concentration gave the crude product which was purified by silica gel chromatography using a Biotage (40 s) column to afford 98 mg (75% yield) of N-[(2-chloro-6-methylphenyl)carbonyl]-4-[1,6-dimethyl-4-(trifluoromethyl)-2-oxo-3-pyridinyl]-L-phenylalanine methyl ester as an amorphous white solid. ES-HRMS m/e calcd for C26H24ClF3N2O4 (M+Na) 543.1268. found 543.1275. b) Preparation of N-[(2-chloro-6-methylphenyl)carbonyl]-4-[1,6-dimethyl-4-(trifluoromethyl)-2-oxo-3-pyridinyl]-L-phenylalanine

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