A solution of triphenylphosphine (160 mg, 0.61 mmol) in methylene chloride (4 mL) was cooled to 0° C. and then slowly treated with N-bromosuccinimide (109 mg, 0.61 mmol). The reaction mixture was stirred at 0° C. for 30 min and then treated with 3-cyclopentyl-2-(4-pyridin-3-yl-phenyl)-propionic acid (150 mg, 0.51 mmol). The resulting reaction mixture was stirred at 0° C. for 5 min and then allowed to warm to 25° C. where it was stirred for 30 min. The reaction mixture was then treated with 2-aminothiazole (112 mg, 1.12 mmol). The resulting reaction mixture was stirred at 25° C. for 15 h. The crude reaction mixture was then directly purified by flash chromatography (Merck Silica gel 60, 230-400 mesh, 100% diethyl ether then 1/1 diethyl ether/ethyl acetate then 1/3 diethyl ether/ethyl acetate) to afford 3-cyclopentyl-2-(4-pyridin-3-yl-phenyl)-N-thiazol-2-yl-propionamide (15 mg, 8%) as a pale yellow foam: mp 48-52° C.; EI-HRMS m/e calcd for C22H23N3OS (M+) 377.1562, found 377.1564.
