反应详情

Employing ethyl 1-(4-fluorophenyl)-5-methyl-6,7-difluoro-1,4-dihydro-4-oxoquinoline-3-carboxylate (0.56 g), conc. hydrochloric acid (1.5 ml), and 90% acetic acid (6 ml), the procedure of Reference Example 10 is repeated to give 1-(4-fluorophenyl)-5-methyl-6,7-difluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid (0.49 g), as white crystals, m.p. 255°-257° C.