A solution of 3-cyclopentyl-2-(4-trifluoromethanesulfonyl-phenyl)propionic acid (164.0 mg, 0.47 mmol) and triphenylphosphine (184.2 mg, 0.70 mmol) in methylene chloride (1.2 mL) was cooled to 0° C. and then treated with N-bromosuccinimide (141.6 mg, 0.80 mmol) in small portions. After the complete addition of N-bromosuccinimide, the reaction mixture was allowed to warm to 25° C. where it was stirred for 1 h. The reaction mixture was then treated with 2-aminothiazole (140.6 mg, 1.40 mmol). The resulting reaction mixture was stirred at 25° C. for 22 h. The reaction mixture was then concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 230-400 mesh, 3/1 hexanes/ethyl acetate) afforded 3-cyclopentyl-N-thiazol-2-yl-2-(4-trifluoromethanesulfonyl-phenyl)-propionamide (47.9 mg, 24%) as a cream solid: mp 189-191° C.; EI-HRMS m/e calcd for C18H19F3N2O3S2 (M+) 432.0789, found 432.0791.
