O=C1O[C:5]([CH2:11][CH2:12][C:13]([O:15]C(C)(C)C)=O)([C:7]([F:10])([F:9])[F:8])[N:4]=C1C(C)C.Cl.[NH2:24]N.C(=O)([O-])[O-].[K+].[K+]>C(O)(=O)C.O>[F:8][C:7]([F:10])([F:9])[C:5]1[CH2:11][CH2:12][C:13](=[O:15])[NH:24][N:4]=18.44 g (26.1 mmol) of tert-butyl 3-[5-oxo-4-(propan-2-yl)-2-(trifluoromethyl)-2,5-dihydro-1,3-oxazol-2-yl]propanoate [CAS Reg. No. 87341-14-8] and 13.44 g (130.5 mmol) of hydrazine hydrochloride were stirred in 100 ml of glacial acetic acid at 118° C. for 2 hours. The reaction solution was then evaporated to dryness under reduced pressure. The residue obtained was taken up in 100 ml of water and made basic using potassium carbonate. The basic solution was subsequently extracted three times with dichloromethane. The combined organic phases were dried over magnesium sulfate, filtered and concentrated to dryness. The crude product was purified chromatographically on silica gel (mobile phase dichloromethane/methanol 50:1→10:1). This gave 2.65 g (15.95 mmol, 61% of theory) of the title compound.
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