Cyclohexylamine → 6-Fluoro-4-hydroxy-1-(4-methoxybenzyl)-2-oxo-1,2-dihydro-[1,8]-naphthyridine-3-carboxylic Acid Cyclohexylamide

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Reaction Conditions

Reaction Steps

Cyclohexylamine (6.14 mL, 53.65 mmol) was added to a stirred solution of 6-fluoro-4-hydroxy-1-(4-methoxy-benzyl)-2-oxo-1,2-dihydro-[1,8]-naphthyridine-3-carboxylic acid ethyl ester (74) (10 g, 26.82 mmol) in xylene and heated at 140° C. for 3 h. The solution was cooled and the solvent was evaporated under vacuum. The residue was suspended in water and extracted by dichloromethane. The combined organic phase was washed by water and brine, then dried over Na2SO4 and evaporated to yield 7.46 g (65%) of 6-fluoro-4-hydroxy-1-(4-methoxy-benzyl)-2-oxo-1,2-dihydro-[1,8]-naphthyridine-3-carboxylic acid cyclohexyl amide (92) as white solids. MP: 176° C.; 1H-NMR (DMSO-d6): δ 1.25-1.41 (m, 5H), 1.54 (m, 1H), 1.66 (m, 2H), 1.87 (m, 2H), 3.68 (s, 3H), 3.86 (m, 1H), 5.51 (s, 2H), 6.81 (d, J=8.8 Hz, 2H), 7.20 (d, J=8.8 Hz, 2H), 8.31 (d, J=8.0 Hz, 1H), 8.83 (s, 1H), 10.24 (s, 1H); EIMS m/z 426 (M+1).

Provenance & Evidence