Hydrochloric Acid → 5-Quinolinecarboxylic acid, 7-fluoro-2-(4-fluorophenyl)-1,2,3,4-tetrahydro-3-(1-methyl-1H-1,2,4-triazol-5-yl)-4-oxo-, methyl ester

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Reaction Steps

To a stirred solution of methyl 7-fluoro-2-(4-fluorophenyl)-1-hydroxy-3-(1-methyl-1H-1,2,4-triazol-5-yl)-4-oxo-1,2,3,4-tetrahydroquinoline-5-carboxylate (10) (41.4 mg, 0.1 mmol) in methanol (5 mL) was added concentrated HCl solution (w/w 37%, 1 mL) and reductive powdered Fe (56 mg, 1 mmol). The reaction mixture was refluxed for 3 hours. After the disappearance of compound (10) as monitored by LC-MS, the reaction system was partitioned between ethyl acetate (20 mL) and water (20 mL) and then the aqueous phase was extracted with ethyl acetate (10 mL×3). The combined organic phase was dried with Na2SO4, concentrated in vacuo and purified by column chromatography (ethyl acetate:petroleum ether=1:1) to give the title compound (5) as a pale yellow solid (12 mg, yield 30%). LC-MS (ESI) m/z: 399 (M+1)+. 1H-NMR (400 MHz, CDCl3) δ (ppm): 3.58 (s, 3H), 3.87 (s, 3H), 4.17 (d, 1H), 4.87 (s, 1H), 5.38 (d, 1H), 6.50 (dd, 2H), 6.99 (dd, 2H), 7.38 (dd, 2H), 7.80 (s, 1H).

Provenance & Evidence