Trifluoroacetic acid → 8,9-Bis(4-fluorophenyl)-8,9-dihydro-2h-pyrido[4,3,2-de]phthalazin-3(7h)-one

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Reaction Steps

A mixture of methyl 2-(4-(dimethoxymethyl)phenyl)-3-(4-fluorophenyl)-4-oxo-1,2,3,4-tetrahydroquinoline-5-carboxylate, ethyl 2-(4-(dimethoxymethyl)phenyl)-3-(4-fluorophenyl)-4-oxo-1,2,3,4-tetrahydroquinoline-5-carboxylate and methyl 2,3-bis-(4-fluorophenyl)-4-oxo-1,2,3,4-tetrahydroquinoline-5-carboxylate (440 mg) and hydrazine monohydrate (20 mL) was stirred under room temperature for overnight. The resulting mixture was evaporated under reduced pressure to 10 mL and then filtered, 400 mg of the crude products were obtained. To a solution of this crude products (400 mg) in dichloromethane was added trifluoroacetic acid (1 ml) at 0° C. The mixture was stirred at room temperature for 1 hr. Then the mixture was neutralized with potassium carbonate. The mixture was extracted with ethyl acetate (50 mL×3). The combined organic layers were washed with brine, dried over anhydrous sodium sulfate, and concentrated to give the crude. The crude product was purified by column chromatography (silica gel, petroleum ether:ethyl acetate 10:1 to 1:1) to give 4-(9-(4-fluorophenyl)-3-oxo-3,7,8,9-tetrahydro-2H-pyrido[4,3,2-de]phthalazin-8-yl)benzaldehyde (80 mg) and 8,9-bis(4-fluorophenyl)-8,9-dihydro-2H-pyrido[4,3,2-de]phthalazin-3(7H)-one (36 mg). 4-(9-(4-fluorophenyl)-3-oxo-3,7,8,9-tetrahydro-2H-pyrido[4,3,2-de]phthalazin-8-yl)benzaldehyde: LC-MS (ESI) m/z: 368 (M+1)+. 8,9-bis(4-fluorophenyl)-8,9-dihydro-2H-pyrido[4,3,2-de]phthalazin-3(7H) -one: 1H-NMR (400 MHz, CD3OD) δ (ppm); 4.29 (d, J=8.0 Hz, 1H), 4.70 (d, J=8.0 Hz, 1H), 6.92-7.00 (m, 4H), 7.08-7.10 (m, 2H), 7.20-7.20 (m, 1H), 7.28-7.32 (m, 2H), 7.59 (m, 1H), 7.63-7.67 (m, 1H). 19F-NMR (400 MHz, CD3OD) δ (ppm): −116.77, −118.23; LC-MS (ESI) m/z: 376 (M+1)+. solid.

Provenance & Evidence