Beta-Alanine → 3-[(1-Benzyl-5-hydroxy-2-oxo-3-phenyl-1,2-dihydro-[1,7]naphthyridine-6-carbonyl)-amino]-propionic acid

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Reaction Steps

A mixture of 1-benzyl-5-hydroxy-2-oxo-3-phenyl-1,2-dihydro-[1,7]naphthyridine-6-carboxylic acid methyl ester (30 mg, 0.078 mmol), β-alanine (692 mg, 7.8 mmol), and NaOMe solution (12 mL, 5.8 mmol, 0.5 M in MeOH) was refluxed for 16 h. After cooling to r.t., solvent was evaporated in vacuo. The residue was partitioned between EtOAc and water. 1 M HCl was added with vigorous stirring until pH about 2. The organic layer was dried over MgSO4 and concentrated. The crude product was purified by silica gel chromatography (0-30% EtOAc/CH2Cl2+1% AcOH). The product isolated was then dissolved in saturated NaHCO3 and washed with ether. The aqueous layer was acidified to pH about 2 with 4 M HCl, and the resulting precipitate was isolated by filtration to give 7.7 mg of the title compound. MS: (+) m/z 444.37 (M+1).

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