反应详情

6,7-Difluoro-1H-benzimidazole-2-thiol (0.34 g, 1.81 mmol) is suspended into 20 mL of tetrahydrofuran (THF) under argon. Then, 130 mg (2.71 mmol) of sodium hydride are added. The reaction mixture is stirred at room temperature until gas evolution has ceased. 5-Nitro-2-furaldehyde (0.25 g, 1.81 mmol) is then added and the reaction mixture is stirred at room temperature for 3 h, upon which it is poured on ice and extracted twice with ethyl acetate. The organic extracts are combined, washed with brine, dried on magnesium sulfate, filtered and concentrated under reduced pressure. The residue is purified by chromatography on a prepacked 70 g 15-40 μm silica gel cartridge (eluting solvent: dichloromethane/THF from 100/0 to 80/20 v/v; rate: 40 mL/min). The fractions containing the desired product are combined and concentrated to dryness under reduced pressure. The residue is purified by chromatography on a prepacked 30 g 15-40 μm silica gel cartridge (eluting solvent: dichloromethane/methanol from 100/0 to 95/5 v/v; rate: 20 mL/min). The fractions containing the desired product are combined and concentrated to dryness under reduced pressure. 0.28 g of 5-(6,7-difluoro-1H-benzimidazol-2-ylsulfanyl)-furan-2-carbaldehyde is obtained as a pale yellow meringue. LCMS-DAD-ELSD: 281(+): [M+H]+.

1. stirringthe reaction mixture is stirred at room temperature for 3 h, upon which it
2. additionis poured on ice
3. extractionextracted twice with ethyl acetate
4. washwashed with brine
5. customdried on magnesium sulfate
6. filtrationfiltered
7. concentrationconcentrated under reduced pressure
8. customThe residue is purified by chromatography on a prepacked 70 g 15-40 μm silica gel cartridge (eluting solvent: dichloromethane/THF from 100/0 to 80/20 v/v; rate: 40 mL/min)
9. additionThe fractions containing the desired product
10. concentrationconcentrated to dryness under reduced pressure
11. customThe residue is purified by chromatography on a prepacked 30 g 15-40 μm silica gel cartridge (eluting solvent: dichloromethane/methanol from 100/0 to 95/5 v/v; rate: 20 mL/min)
12. additionThe fractions containing the desired product
13. concentrationconcentrated to dryness under reduced pressure