反应详情

To 1,3-dimethyl-4-nitro-1H-pyrazole-5-carboxylic acid (1.08 g, 5.84 mmol) in anhydrous dichloromethane (DCM) (25 mL) and DMF (0.5 mL) was added dropwise oxalyl chloride (0.74 mL, 8.77 mmol, 1.5 eq.) over 10 minutes. The reaction mixture was stirred at RT under N2 for 17 hours. Volatile solvent was evaporated in vacuo, and the crude material dissolved in anhydrous THF (20 mL) and acetone (10 mL). Concentrated aqueous ammonium hydroxide (5.0 mL, 128.4 mmol, 22 eq.) was added slowly, and the reaction mixture was stirred at RT for 16 hours. The reaction mixture was concentrated in vacuo, and the residue was diluted with ethyl acetate. The organic layer was washed with saturated aqueous solution of sodium bicarbonate, water and brine, dried (Na2SO4), filtered and concentrated in vacuo. Trituration from ether-heptane afforded the desired product as a white solid (550.0 mg, 51.5%). 1H NMR (DMSO-d6, 500 MHz) δ ppm 8.39 (broad s, 1H), 8.21 (broad s, 1H), 3.77 (s, 3H), 2.42 (s, 3H).

1. customVolatile solvent was evaporated in vacuo
2. dissolutionthe crude material dissolved in anhydrous THF (20 mL)
3. stirringthe reaction mixture was stirred at RT for 16 hours
4. concentrationThe reaction mixture was concentrated in vacuo
5. additionthe residue was diluted with ethyl acetate
6. washThe organic layer was washed with saturated aqueous solution of sodium bicarbonate, water and brine
7. dry with materialdried (Na2SO4)
8. filtrationfiltered
9. concentrationconcentrated in vacuo