4,6-Dichloro-1-(4-methoxy-benzyl)-2-oxo-1,2-dihydro-[1,8]-naphthyridine-3-carboxylic Acid Ethyl Ester → 4,6-Dichloro-2-oxo-1,2-dihydro-[1,8]-naphthyridine-3-carboxylic Acid Ethyl Ester

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Reaction Steps

A solution of 4,6-dichloro-1-(4-methoxy-benzyl)-2-oxo-1,2-dihydro-[1,8]-naphthyridine-3-carboxylic acid ethyl ester (77) (6.0 g, 14.73 mmol) in neat TFA was refluxed for 3 h. The solution was cooled and the excess TFA was distilled under vacuum. The residue was suspended in saturated NaHCO3 solution, sonicated briefly and filtered. The solids were washed by water, and dried at room temperature to yield 4.2 g (99%) of 4,6-dichloro-2-oxo-1,2-dihydro-[1,8]-naphthyridine-3-carboxylic acid ethyl ester (79) as white solids. MP: 228° C.; 1H-NM (DMSO-d6): δ 1.29 (t, J=7.2 Hz, 3H), 4.37 (q, J=7.2 Hz, 2H), 8.38 (d, J=2.4 Hz, 1H), 8.75 (d, J=2.4 Hz, 1H), 13.10 (s, 1H); EIMS: 287 (M).

Provenance & Evidence