The reactions of 3-fluoro-4-R-6-phenylsulfonylmethylnitrobenzenes with dimethyl fumarate or diethyl maleate in acetonitrile in the presence of an excess of K2CO3 and a catalytic amount of 18-crown-6 afforded mixtures of dialkyl 6-R-7-fluoro- and dialkyl 6-R-7-phenylsulfonylquinoline-2,3-carboxylate N-oxides, as well as dialkyl 6-R-7-fiuoro- quinoline-2,3-carboxylates (alkyl is methyl or ethyl), which were resolved by column chromatography and identified by 1H NMR spectroscopy and X-ray diffraction.