Carbon Dioxide → 1-Cyclopropyl-6-fluoro-8-methyl-7-(isoindolin-5-yl)-1,4-dihydro-4-oxoquinoline-3-carboxylic acid

Participants

Reaction Steps

In 5.3 ml of 47% hydrobromic acid was suspended 0.53 g of 1-cyclopropyl-6-fluoro-8-methyl-7-[2-(p-toluenesulfonyl)isoindolin-5-yl]-1,4-dihydro-4-oxoquinoline-3 carboxylic acid, and 0.28 g of phenol and 3.2 ml of propionic acid were added to the suspension, after which the resulting mixture was heated under reflux for one hour under a nitrogen stream. The reaction mixture was concentrated under reduced pressure, and ethanol was added to the residue obtained, after which the crystals formed were collected by filtration, to obtain 0.38 g of colorless, crystalline 1-cyclopropyl-6-fluoro-8-methyl-7-(isoindolin-5-yl)-1,4-dihydro-4-oxoquinoline-3-carboxylic acid hydrobromide. The hydrobromide obtained was suspended in 3.8 ml of ethanol and then dissolved in 7.6 ml of 0.5N aqueous sodium hydroxide solution, after which a carbon dioxide gas was blown into the solution. The crystals formed were collected by filtration, to obtain 0.27 g of colorless, crystalline 1-cyclopropyl-6-fluoro-8-methyl-7-(isoindolin-5-yl)-1,4-dihydro-4-oxoquinoline-3-carboxylic acid.

Provenance & Evidence