Beta-Alanine → 3-{[7-(2,4-Dimethoxy-benzyl)-4-hydroxy-8-oxo-5,6,7,8-tetrahydro-[2,7]naphthyridine-3-carbonyl]-amino}-propionic acid

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Reaction Steps

A mixture of 7-(2,4-dimethoxy-benzyl)-4-hydroxy-8-oxo-5,6,7,8-tetrahydro-[2,7]naphthyridine-3-carboxylic acid methyl ester (19 mg, 0.051 mmol), β-alanine (605 mg, 6.79 mmol), and NaOMe solution (10 mL, 5.11, 0.5 M in MeOH) was refluxed for 16 h. After the mixture was cooled to r.t., solvent was evaporated in vacuo. The residue was partitioned between EtOAc and water, and 1 M HCl was added with vigorous stirring until pH about 1. The organic layer was dried over MgSO4 and concentrated. The crude was first purified by silica gel chromatography (5-80% EtOAc/hexanes+2% AcOH), and the product isolated was then dissolved in saturated NaHCO3. The aqueous solution was washed with ether, acidified to pH about 1 with 4 M HCl, and the resulting precipitate was collected by filtration and dried under vacuum to give 7.3 mg of the title compound. MS: (+) m/z 430.27 (M+1).

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