Acetic Acid → 5-Amino-1-cyclopropyl-8-difluoromethoxy-6,7-difluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid

Participants

Reaction Steps

A suspension of 3.58 g (0.0096 moles) of ethyl 5-amino-1-cyclopropyl-8-difluoromethoxy-6,7-difluoro-1,4-dihydro-4-oxoquinoline-3-carboxylate [(XXII), R1 =--OCHF2, R17 =C2H5, X=F] [prepared as described in step (f) or (f') above], 21 ml of acetic acid, 2.8 ml of concentrated sulfuric acid and 15 ml of water was heated under reflux, with stirring, for 1 hour, after which it was cooled by allowing it to stand. Water was then added to the reaction mixture, and the insoluble materials were removed by filtration and washed with water and with diethyl ether, in that order, to give 3.0 g of 5-amino-1-cyclopropyl-8-difluoromethoxy-6,7-difluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid as a pale yellowish green powder, melting at 284°-286° C.

Provenance & Evidence