A method for the synthesis of rufloxacin aspartate [i.e., a quinolone antibacterial agent] is reported here.The above-mentioned title compound was obtained using 9,10-difluoro-7-oxo-7H-pyrido[1,2,3-de][1,4]benzothiazine-6-carboxylic acid as a starting material.A reaction of the this carboxylic acid with boron fluoride (BF3)-acetonitrile provided 9,10-difluoro-2,3-dihydro-7-oxo-7H-pyrido[1,2,3-de]-1,4-benzothiazine-6-carboxylic acid anhydride with B,B-difluoroborinic acid.Further reaction with methylpiperazine and hydrolysis delivered rufloxacin which was then converted into the desired aspartate salt.The product structures were confirmed by spectroscopic methods.The overall product yield was 62.7%.This synthetic method is suitable for industrial production (no data).