Pyridine → N-benzooxazol-2-yl-3-cyclopentyl-2-(3,4-dichloro-phenyl)-propionamide

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A solution of triphenylphosphine (274 mg, 1.04 mmol) in methylene chloride (6 mL) was cooled to 0° C. and then treated with N-bromosuccinimide (211 mg, 1.18 mmol). The resulting brownish-purple mixture was stirred at 0° C. for 5 min until the reaction mixture became homogeneous. The reaction mixture was then treated with 3-cyclopentyl-2-(3,4-dichloro-phenyl)-propionic acid (prepared as in Example 1, 200 mg, 0.70 mmol). The reaction mixture was stirred at 0° C. for 20 min and then allowed to warm to 25° C. where it was stirred for 30 min. The reaction mixture was then treated with 2-aminobenzoxazole (140 mg, 1.04 mmol) and pyridine (0.17 mL, 2.09 mmol), and the reaction mixture was allowed to stir at 25° C. for 20 h. The resulting reaction mixture was diluted with water (15 mL) and then extracted with methylene chloride (3×15 mL). The combined organic layers were dried over sodium sulfate, filtered, and concentrated in vacuo. Biotage chromatography (FLASH 40S, Silica, 80/20 hexanes/ethyl acetate) afforded N-benzoxazol-2-yl-3-cyclopentyl-2-(3,4-dichloro-phenyl)-propionamide (214 mg, 76%) as a light yellow foam: EI-HRMS m/e calcd for C21H20Cl2N2O2 (M+) 402.0902, found 402.0908.

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