Hydrochloric Acid → {2-[3-Cyclopentyl-2-(4-nitro-phenyl)-propionylamino]-thiazol-4-yl}-acetic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

A solution of 3-cyclopentyl-2-(4-nitro-phenyl)-propionic acid (prepared as in Example 22A, 263.0 mg, 1.0 mmol) in N,N-dimethylformamide (10 mL) was treated with O-benzotriazol-1-yl-N,N,N′,N′-tetramethyluronium hexafluorophosphate (379 mg, 1.0 mmol), (2-amino-thiazol-4-yl)-acetic acid ethyl ester (279 mg, 1.5 mmol) and N,N-diisopropylethylamine (0.34 mL, 2.0 mmol). The reaction mixture was stirred at 25° C. for 5 h. The reaction mixture was then poured into a 2N aqueous hydrochloric acid solution (25 mL) and extracted with ethyl acetate (3×25 mL). The combined organic layers were washed with water (1×75 mL), a saturated aqueous sodium bicarbonate solution (1×75 mL), and a saturated aqueous sodium chloride solution (3×75 mL), dried over sodium sulfate, filtered and concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 230-400 mesh, 70/30 hexanes/ethyl acetate) afforded {2-[3-cyclopentyl-2-(4-nitro-phenyl)-propionylamino]-thiazol-4-yl }-acetic acid ethyl ester (70.0 mg, 39.4%) as a pale yellow oil: FAB-HRMS m/e calcd for C21H25N3O5S (M+H)+ 432.1593, found 432.1595.

Provenance & Evidence