Acetic Acid → 5-Amino-1-cyclopropyl-8-difluoromethoxy-6,7-difluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid

Participants

Reaction Steps

The preparation comprises refluxing mixture of reducing iron powder (2.4 g, 42.8 mmol), water (4.5 mL) and acetic acid (0.3 mL) for 15 min under stirring, adding batch-wise ethyl 1-cyclopropyl-6,7-difluoro-8-difluoromethoxyl-5-nitro-1,4-dihydro-4-oxoquinoline-3-carboxylate (4.3 g, 10.6 mmol), adding ethanol (20 mL), continuously refluxing for 6 h under stirring, hot filtering, distilling off the solvent from the filtrate, adding concentrated hydrochloric acid (5 mL) and acetic acid (10 mL) to react at 100° C. for 1 h, cooling to room temperature, filtering, adding ethanol (10 mL) to the filter cake to reflux for 0.5 h, cooling to room temperature, filtering, and drying obtained filter cake to give a pale yellow solid product 5-amino-1-cyclopropyl-6,7-difluoro-8-difluoromethoxyl-1,4-dihydro-4-oxoquinoline-3-carboxylic acid (3.1 g, 84.5%).

Provenance & Evidence