C(O[C:4]([C:6]1[S:7][CH:8]=[C:9]([C:11]([F:14])([F:13])[F:12])[N:10]=1)=[O:5])C.[CH3:15][CH2:16][O:17][C:18]([CH3:20])=[O:19].C(O[K])(C)(C)C>C1(C)C=CC=CC=1>[O:5]=[C:4]([C:6]1[S:7][CH:8]=[C:9]([C:11]([F:12])([F:13])[F:14])[N:10]=1)[CH2:20][C:18]([O:17][CH2:16][CH3:15])=[O:19]To a solution of 4-trifluoromethylthiazole-2-carboxylic acid ethylester (8.88 mmol) in toluene (50 mL) were added successively EtOAc (13.32 mmol) and tBuOK (17.76 mmol). The resulting mixture was stirred at 100° C. for 1 hr. The solvent was removed by evaporation and water and Et2O were added. The solution was neutralized with acetic acid. The extract was washed with water and the organic layer was dried over Na2SO4, filtered, and concentrated under reduced pressure to give compound 28 as a yellow oil in 45% yield. MS (ESI, EI−): m/z=266 (MH−).
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