Dimethyl Sulfoxide → HCID 19848074, compound

Participants

Reaction Conditions

Reaction Steps

A mixture of 5.18 g of piperazine and 6.37 g of an anhydride of 6-fluoro-7-chloro-1-methylamino-4-oxo-1,4-dihydro-quinoline-3-carboxylic acid and difluoroboric acid formed with 32 ml of dimethyl sulfoxide is stirred at 110° C. for 3 hours. To the reaction mixture 51 ml of a 6 weight/vol % aqueous sodium hydroxide solution are added and the aqueous reaction mixture is stirred under slight boiling for 2 hours. The reaction mixture is filtered, the filtrate is evaporated in vacuo to two-thirds of its volume and the pH of the solution is adjusted to 6.5-7 by adding acetic acid. The reaction mixture is allowed to crystallize in a refrigerator overnight. Next morning the precipitated crystals are filtered, washed twice with 10 ml of water each and with 5 ml of methanol. Thus 5.3 g of 6-fluoro-1-ethylamino-7-piperazino-4-oxo-1,4-dihydro-quinoline-3-carboxylic acid are obtained. Yield: 82%. Mp.: 289°-291° C. (decomposition; from dimethyl formamide).

Provenance & Evidence