反应详情

Employing ethyl 1-(2,4-difluorophenyl)-5-methyl-6,7,8-trifluoro-1,4-dihydro-4 -oxoquinoline-3-carboxylate (4.3 g) and conc. hydrochloric acid: 90% acetic acid (1:4) (80 ml), the procedure of Reference Example 23 is repeated to give 1-(2,4-difluorophenyl)-5-methyl-6,7,8-trifluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid (2.93 g), as white powder, m.p. 221°-222° C.