ðɪs lˈæst ˌɪntɚmˈiːdiət ɪz ðˈɛn tˈeɪkən ˌɔn tə ðə kwˈɪnəlˌoʊn nˈaɪn baɪ ᵻsˈɛnʃəli ðə sˈeɪm skˈiːm æz ðæt jˈuːzd tə pɹɪpˈɛɹ dˈɪfləksˌæsɪn, wɪððə dˈɪfɹəns ðætðə tʃˈeɪn iːlˌɑːŋɡˈeɪʃən ɪz baɪ mˈiːnz ʌv ɡɹˈɪɡnɑːɹd ɹɪˈeɪdʒənt ʌv ˈɛθəl bɹˈɑːmoʊsˌɪɾeɪt.
This last intermediate is then taken on to the quinolone (9)  by essentially the same scheme as that used to prepare difloxacin, with the difference that the chain elongation is by means of Grignard reagent of ethyl bromoacetate.