The invention discloses a
high selectivity method for synthesizing
moxifloxacin. The method comprises the following steps of: reacting boric anhydride with trifluoro
acetic anhydride to obtain a chelant; reacting 1-cyclopropyl-6,7-difluoro-1,4-dihydro-8-methoxy-4-oxo-3-quinolinecarboxylic acid
ethyl ester with the chelant, cooling to
room temperature, adding
ice water, performing suction
filtration, and washing a
filter cake with water until neutrality to obtain a 1-ethyl-7-chloro-6-fluoro-1,4-dihydro-4-oxoquinoline-3-
carboxylic acid methyl ester
trifluoroacetic anhydride boronized chelate; and reacting the 1-ethyl-7-chloro-6-fluoro-1,4-dihydro-4-oxoquinoline-3-
carboxylic acid methyl ester
trifluoroacetic anhydride boronized chelate with (S,S)-2,8-diazabicyclo[4,3,0]
nonane to obtain a 1-cyclopropyl-6-fluoro-7-([S,S]-2,8-diazabicyclo[4,3,0]
nonane-8-methoxy-4-oxo-1,4-dihydro-3-quinolinecarboxylic acid
ethyl ester trifluoroacetic anhydride boronized chelate, recycling a
solvent under reduced pressure, adding alkali, refluxing, discoloring, filtering, freezing, performing suction
filtration, and
drying a
filter cake. The method is simple, mild in conditions, and high in selectivity, avoids difficultly separated impurities, is high in reaction yield and product purity, and is suitable for industrial production.