260430-93-1

General procedure for the synthesis of 6-fluoroquinoline-2-carbaldehyde from 6-fluoro-2-methylquinoline: a mixture of compound 6 (0.48 g, 3.0 mmol) with selenium dioxide (0.66 g, 6.0 mmol) in 1,4-dioxane (50 mL) was heated and reacted for 2 hr at 100 °C (the reaction progress was monitored by TLC). Upon completion of the reaction, the mixture was cooled and treated with 5% aqueous NaHCO3 (80 mL) followed by extraction with dichloromethane (50 mL x 3). The organic layers were combined and dried with anhydrous magnesium sulfate, followed by evaporation of the solvent. The crude product was crystallized by ethanol to give compound 7 (0.43 g, 81% yield) as a white solid. Next, compound 7 (0.36 g, 2.0 mmol) was stirred with the corresponding acetophenone (2.0 mmol) at 0 °C for 15 min. Six equivalents of aqueous KOH solution was added and the reaction mixture was stirred at room temperature for 12 hours (the progress of the reaction was monitored by TLC). After completion of the reaction, the reaction mixture was adjusted to pH 3 by adding 1 M HCl to the reaction mixture and extracted with ethyl acetate (50 mL x 3). The organic layers were combined, dried with anhydrous magnesium sulfate and concentrated in vacuum. The crude products were obtained as quinolinyl chalcone derivatives 8a-c by purification and crystallization with ethanol.

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