Beta-Alanine → 3-[(1-Cyclohexylmethyl-5-hydroxy-2-oxo-3-phenyl-8-pyridin-4-yl-1,2-dihydro-[1,7]naphthyridine-6-carbonyl)-amino]-propionic acid

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Reaction Steps

A mixture of 1-cyclohexylmethyl-5-hydroxy-2-oxo-3-phenyl-8-pyridin-4-yl-1,2-dihydro-[1,7]naphthyridine-6-carboxylic acid methyl ester (46 mg, 0.098 mmol), β-alanine (699 mg, 7.8 mmol) and NaOMe solution (11.8 mL, 5.9 mmol, 0.5 M in MeOH) was refluxed for 16 h. After the mixture was cooled to r.t., the solvent was evaporated in vacuo. The residue was partitioned between EtOAc and water. 1 M HCl was added with vigorous stirring until pH was about 3-4. The aqueous layer was extracted with additional EtOAc, and the organic layers were combined, dried over MgSO4 and concentrated. The crude product was purified by silica gel chromatography (5-100% EtOAc/hexanes+1% AcOH). The product isolated was dissolved in saturated NaHCO3 and washed several times with ether. The aqueous layer was acidified to pH about 3-4, and the resulting precipitate was isolated by filtration to give 5 mg of the title compound. MS: (+) m/z 527.45 (M+1).

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