[CH:1]1([CH2:4][C@H:5]([NH:12]C(=O)OC(C)(C)C)[C:6]2[N:10]=[C:9]([CH3:11])[O:8][N:7]=2)[CH2:3][CH2:2]1.O>Cl>[CH:1]1([CH2:4][C@H:5]([NH2:12])[C:6]2[N:10]=[C:9]([CH3:11])[O:8][N:7]=2)[CH2:3][CH2:2]1A solution of (S)-tert-butyl 2-cyclopropyl-1-(5-methyl-1,2,4-oxadiazol-3-yl)ethylcarbamate (0.5 g, 2 mmol) in sat. hydrochloric acid (10 mL) was stirred at room temperature for 1 h. Then water (20 mL) was added. The water phase was washed with ethyl acetate (2×20 mL) and adjusted with 2 M sodium hydroxide solution to pH=9-10. It was then extracted with ethyl acetate (2×20 mL). The organic layer was washed with brine (20 mL), dried over anhydrous sodium sulfate and concentrated to give crude product as a white solid (0.25 g, 80%); MS (EI): m/e 168.2 [M+H]+.
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