Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

N-Alkylation of ethyl 6,7,8-trifluoro-1,4-dihydro-4-oxoquinoline-3-carboxylate (Vg) with 3-bromopropyne followed by acidic hydrolysis provided N-propyl derivative Ic which in alkaline media yielded N-propadienyl derivative IId. Propadienyl derivatives IIa and IIb treated with primary or secondary amines provided intermediates IIIa-IIIc which were hydrolyzed to N-acetonyl derivatives IVa and IVb, respectively. N-Benzylation of ethyl 7-chloro-6-fluoro-1,4-dihydro-4-oxoquinoline-3-carboxylate (Va) followed by hydrolysis yielded 1-benzyl-7-chloro-6-fluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid (Vd) which upon a treatment with N-methylpiperazine provided Ve. Compound Ve was hydrogenated on Pd to 6-fluoro-1,4-dihydro-7-(4-methyl-1-piperazinyl)-4-oxoquinoline-3-carboxylic acid (Vf).