反应详情

1-Phenyl-5-(trifluoromethyl)-1H-pyrazole-4-carboxylic acid (2 g, 7.81 mmol), HOBT (1.315 g, 8.59 mmol) and EDC (1.646 g, 8.59 mmol) were dissolved in DMF (18 mL) under nitrogen at room temperature. The resulting clear, pale yellow solution was stirred for 20 minutes, then N-hydroxy-4-(hydroxymethyl)benzimidamide, Int.2, (1.297 g, 7.81 mmol) was added in several portions. The reaction was placed in an oil bath preheated to 140° C. for 10 hours. The reaction was cooled to room temperature, poured into water (150 mL), stirred vigorously and placed in a sonicator bath for 1 hour. The solids were collected by filtration, washed with water, air dried and then placed under vacuum to give (4-(5-(1-phenyl-5-(trifluoromethyl)-1H-pyrazol-4-yl)-1,2,4-oxadiazol-3-yl)phenyl)methanol (2.5 g, 6.47 mmol) as a very light yellow solid. The compound had an HPLC retention time=3.76 min.−Column: CHROMOLITH® SpeedROD 4.6×50 mm (4 min.); Solvent A=10% MeOH, 90% H2O, 0.2% H3PO4; Solvent B=90% MeOH, 10% H2O, 0.2% H3PO4. LC/MS M+1=387.1 1H NMR (500 MHz, MeOD) δ ppm 4.70 (s, 2H), 7.53-7.57 (m, 4 H), 7.57-7.62 (m, 1H), 7.61 (d, J=6.4 Hz, 2H), 8.12 (d, J=8.2 Hz, 2H), 8.48 (s, 1H).

1. customThe reaction was placed in an oil bath
2. waitpreheated to 140° C. for 10 hours
3. stirringstirred vigorously
4. waitplaced in a sonicator bath for 1 hour
5. filtrationThe solids were collected by filtration
6. washwashed with water, air
7. customdried