[C:1]([NH:8][C@H:9]([C:13]([OH:15])=O)[CH:10]([CH3:12])[CH3:11])([O:3][C:4]([CH3:7])([CH3:6])[CH3:5])=[O:2].N1C=CC=CC=1.N1C(F)=NC(F)=NC=1[F:24]>C(Cl)Cl>[C:4]([O:3][C:1](=[O:2])[NH:8][C@H:9]([C:13]([F:24])=[O:15])[CH:10]([CH3:12])[CH3:11])([CH3:7])([CH3:6])[CH3:5]To an oven-dried, septaed 25 mL round-bottom flask, cooled under an argon atmosphere, and charged with (S)-N-BOC-valine (217.2 mg, 1.00 mmol) was added 2.5 mL CH2Cl2, and pyridine (81 μL, 1.00 mmol). The solution was cooled to −15° C., and to the reaction was added cyanuric fluoride (450 μL, 5.0 mmol). The reaction was stirred at −15° C. for 60 minutes, with the gradual formation of a white precipitate. Without warming, the crude reaction was poured over ice, and immediately extracted twice with CH2Cl2. The combined CH2Cl2 extracts were washed once with ice-cold water, dried over anhydrous magnesium sulfate, and concentrated in vacuo to afford 201.3 mg of 25g as white needles. FTIR (neat) 1847 cm−1.
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