Potassium Nitrate → Ethyl 1-cyclopropyl-8-difluoromethoxy-6,7-difluoro-5-nitro-1,4-dihydro-4-oxoquinoline-3-carboxylate

Participants

Reaction Steps

The preparation comprises dissolving ethyl 1-cyclopropyl-6,7-difluoro-8-difluoromethoxyl-1,4-dihydro-4-oxoquinoline-3-carboxylate (target product of embodiment 3, 1.0 g, 2.8 mmol) in concentrated sulfuric acid (10 mL), slowly adding potassium nitrate (2.0 g, 19.8 mmol), reacting for 1 h at 40° C., cooling down to room temperature, charging the reaction mixture into ice water (100 mL), stirring, filtering, treating obtained filter cake with ethanol (20 mL), refluxing for 0.5 h, cooling down to room temperature, filtering, and drying obtained filter cake to give ethyl 1-cyclopropyl-6,7-difluoro-8-difluoromethoxyl-5-nitro-1,4-dihydro-4-oxoquinoline-3-carboxylate (0.5 g, 45.5%).

Provenance & Evidence