1,2-Dichloroethane → (S)-2-Amino-1-(3-phenyl-[1,2,4]oxadiazol-5-yl)-butan-1-one

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Reaction Steps

3-tert-Butoxycarbonylamino-2-hydroxy-pentanoic acid (500 mg, 2.14 mmol) was combined with EDC (600 mg, 3.14 mmol), HOBt (600 mg, 3.92 mmol), and N-hydroxy-benzamidine (292 mg, 2.14 mmol). Dichloromethyl (10 mL) was added and then 4-methylmorpholine (1 mL). The mixture was stirred at ambient temperature for 16 hours. After dilution with ethyl acetate (200 mL), the solution was washed with water (30 mL), saturated aqueous NaHCO3 solution and brine, dried with MgSO4 and evaporated under vacuum. The crude product was dissolved in pyridine (10 mL) and heated at 80° C. for 15 hours. The pyridine was evaporated under vacuum and the residue was purified by flash chromatography on silica gel (eluent: ethyl acetate) to yield 290 mg (0.83 mmol). The oxadiazole (145 mg, 0.41 mmol) was dissolved in CH2Cl2 (4 mL) and TFA (4 mL) was added. After stirring for 1 hour, the mixture was evaporated to dryness to yield (S)-2-Amino-1-(3-phenyl-[1,2,4]oxadiazol-5-yl)-butan-1-one.

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