[OH-].[K+].[N+:3]([CH2:5][C:6]([NH2:8])=[O:7])#[C-:4].[F:9][C:10]([F:20])([F:19])[C:11]1[CH:18]=[CH:17][C:14]([CH:15]=[O:16])=[CH:13][CH:12]=1>CO>[F:9][C:10]([F:19])([F:20])[C:11]1[CH:12]=[CH:13][C:14]([C@H:15]2[O:16][CH:4]=[N:3][CH:5]2[C:6]([NH2:8])=[O:7])=[CH:17][CH:18]=1To a cooled (˜10° C.) solution of KOH (13.2 g, 235 mmol) in MeOH (50 mL) was added the solution of 2-isocyanoacetamide (LXXIV) in MeOH (60 mL) dropwise while maintaining the temperature at 10-15° C. A solution of 4-(trifluoromethyl)benzaldehyde (40.9 g, 235 mmol) in MeOH (50 mL) was then added and the reaction was stirred for an additional 2 h. The reaction mixture was cooled to −20° C. causing a white solid to precipitate. The solid was filtered and dried to give crude (5R)-5-(4-(trifluoromethyl)phenyl)-4,5-dihydrooxazole-4-carboxamide (LXXV) (62 g). The crude product was used for the next step without purification.
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