Hydrochloric Acid → 2-(4-Cyanobutyl)-6-(5-methyl-2-phenyl-4-oxazolylmethoxy)benzofuran

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反応手順

Sodium hydride (60%, oily, 0.20 g) was gradually added to a solution of 3-cyanopropyltriphenylphosphonium bromide (2.07 g) in N,N-dimethylformamide (30 ml) at room temperature, followed by stirring for 1 hour. 6-(5-Methyl-2-phenyl-4-oxazolylmethoxy)benzofuran-2-carboaldehyde (1.40 g) was added, followed by stirring at 70° to 80° C. for 2 hours. The reaction mixture was poured over ice water and neutralized with 2N hydrochloric acid, followed by extraction with ethyl acetate (200 ml). After the ethyl acetate layer was washed with water and dried (MgSO4), the solvent was distilled off; the residue was subjected to silica gel column chromatography. From the fraction eluted with ethyl acetate-hexane (1:2, v/v), an oily substance was obtained, which was dissolved in tetrahydrofuran (40 ml). To this solution, palladium-carbon (5%, 0.70 g) was added, followed by catalytic reduction at room temperature and under an atmospheric pressure of 1 atm. The catalyst was filtered off, the filtrate was concentrated; the residue was subjected to silica gel column chromatography. From the fraction eluted with ethyl acetate-hexane (1:3, v/v), crystals of 2-(4-cyanobutyl)-6-(5-methyl-2-phenyl-4-oxazolylmethoxy)benzofuran (0.97 g, 60%) were obtained, which was then recrystallized from diethyl ether-hexane to yield colorless prisms having a melting point of 87° to 88° C.

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