1-Methylpiperazine → Levofloxacin

Participants

Reaction Conditions

Reaction Steps

3 g (10.67 mmole) of (S)-(−)-9,10-difluoro-3-methyl-7-oxo-2,3-dihydro-7H-pyrido [1,2,3-de] [1,4]benzoxazine-6-carboxylic acid was put in suspension in 21 mL of isobutanol and 4.75 mL (43 mmole) of N-methyl piperazine. The reaction mixture was heated to reflux for 6 hours, then slurried at ambient temperature for 60 hours and heated again to reflux for 7 hours until completion of the reaction. During that time, the reaction mixture became soluble at reflux temperature. The mixture was then cooled to 0° C., filtered under vacuum, washed with 7 mL isobutanol and 10 mL n-heptane, and dried overnight to obtain 2.83 g (77.3%) of levofloxacin.

Provenance & Evidence