Sodium hydride → (E)-2-Styryl-1-(3-trifluoromethylpyridin-2-yl)-1H-benzimidazole

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a stirred solution of (E)-2-styryl-1H-benzimidazole (0.49 g, 2.2 mmol) in dimethylacetamide (20 ml) at 0° C. under a nitrogen atmosphere was added sodium hydride (0.11 g, 2.8 mmol). After stirring at 0° C. for 20 min. and then at room temperature for 30 min., a solution of 2-Chloro-3-trifluoromethylpyridine (0.60 g, 3.3 mmol) in dimethylacetamide (5 ml) was added. The resulting mixture was heated to reflux for about 3 h 20 min. After cooling, copper bronze (0.45 g, 7.1 mg-atom) was added and heating was continued for 9 h 20 min. The reaction mixture was filtered through a pad of celite and the filtrate was diluted with dichloromethane (200 ml), washed consecutively with water (3×200 ml) and brine (100 ml), dried (magnesium sulfate) and concentrated to dryness. Purification by column chromatography (silica gel, 150 g; n-hexane/ethyl acetate (2/1)) followed by recrystallization from a mixture of isopropyl ether and n-hexane yielded 37 mg (5%) of the titled compound as white solids. MW: 365.36; mp: 156.0-157.0° C.; 1H-NMR (CDCl3) δ: 8.96 (1H, dd, J=4.8, 1.8 Hz), 8.36 (1H, dd, J=8.1, 1.8 Hz), 7.90 (1H, d, J=15.8 Hz), 7.84 (1H, d, J=8.1 Hz), 7.76 (1H, d, J=8.1, 4.8 Hz), 7.45-7.20 (7H, m), 6.92 (1H, d, J=7.7 Hz), 6.47 (1H, d, J=15.8 Hz).

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