Beta-Alanine → 3-[(1-Benzyl-5-cyano-8-hydroxy-2-oxo-1,2-dihydro-[1,6]naphthyridine-7-carbonyl)-amino]-propionic acid

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Reaction Steps

A mixture of 1-benzyl-5-cyano-8-hydroxy-2-oxo-1,2-dihydro-[1,6]naphthyridine-7-carboxylic acid methyl ester (20 mg, 0.060 mmol), β-alanine (532 mg, 6.0 mmol) and NaOMe solution (9.6 mL, 4.8 mmol, 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. 1 M HCl was added with vigorous stirring until pH about 2. The organic layer was dried over MgSO4 and concentrated. The residue was taken up in saturated NaHCO3 and washed several times 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 12 mg of the title compound as a pale pink solid. MS: (−) m/z 391.35 (M−1).

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