1-Hydroxybenzotriazole → 5-(5-Nitro-1H-pyrazol-3-yl)-3-[4-(trifluoromethoxy)phenyl]-1,2,4-oxadiazole

To a mechanically stirred solution of 5-nitro-1H-pyrazole-3-carboxylic acid (1.0 g, 6.24 mmol) in dry DMF (50 mL) was added EDCl (1.20 g, 6.24 mmol), HOBT (0.84 g, 6.24 mmol) and N′-hydroxy-4-(trifluoromethoxy)benzenecarboximidamide (1.37 g, 6.24 mmol). The mixture was stirred at rt for 2 h, and then warmed to 140° C. and stirred for additional 2 h. After being cooled to rt, the mixture was diluted with water (100 mL) and extracted with ethyl acetate. The organic extract was successively washed with water and brine. After drying over anhydrous magnesium sulfate and filtration, the solvent was removed in vacuo, and the residue was redissolved in warm acetonitrile (3 mL) to which tert-butyl methyl ether (2 mL) was added. The title compound precipitated and was obtained as a white solid after filtration, washing with tert-butyl methyl ether and drying in vacuo (1.2 g, 56%): 1H NMR (500 MHz, DMSO-d6) δ 8.20 (d, 2H), 7.58 (d, 2H), 7.34 (s, 1H); ES-MS m/z 340 (M-H)−; HPLC RT (Method J) 4.87 min.

1. temperaturewarmed to 140° C.
2. stirringstirred for additional 2 h
3. temperatureAfter being cooled to rt
4. extractionextracted with ethyl acetate
5. extractionThe organic extract
6. washwas successively washed with water and brine
7. dry with materialAfter drying over anhydrous magnesium sulfate and filtration
8. customthe solvent was removed in vacuo
9. dissolutionthe residue was redissolved in warm acetonitrile (3 mL) to which tert-butyl methyl ether (2 mL)
10. additionwas added
11. customThe title compound precipitated
12. customwas obtained as a white solid
13. filtrationafter filtration
14. washwashing with tert-butyl methyl ether
15. customdrying in vacuo (1.2 g, 56%)
16. customHPLC RT (Method J) 4.87 min.

ORD-Eintrag

ord-6544fd9b5ae8465e96963cafef4c15a9

Quelldatensatz

uspto-grants-2014_08

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US08796253B2