Dimethyl Sulfoxide → Levofloxacin Hydrate

Participants

Reaction Conditions

Reaction Steps

In 1 liter reactor equipped with a mechanical stirrer, a condenser and a thermometer, heated at 80° C., was charged 87.5 g (0.31 mole) of (S)-(−)-9,10-difluoro-3-methyl-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid, 61.3 mL DMSO and 86.3 mL (0.77 mole) of N-methylpiperazine. The slurry was stirred at a rate of 250 rpm under nitrogen atmosphere at 80° C. until completion of the reaction (monitoring by HPLC). Then the slurry was cooled to 75° C. and a mixture of isopropanol (675 mL) and water (25 mL) was added dropwise at this temperature during 2 hours. The slurry was then cooled to 5° C. during 4 hours, maintained at this temperature for 2 hours and filtrated under vacuum at this temperature. The solid was then washed with 175 mL of isopropanol (2 rinses) and dried under vacuum to obtain levofloxacin hemihydrate.

Provenance & Evidence