反应详情

4,5,6-Trifluoro-1,3-dihydro-benzimidazole-2-thione (0.72 g, 3.52 mmol) is suspended into 40 mL of tetrahydrofuran under argon. Then, 0.3 g (7.1 mmol) of sodium hydride are added. The reaction mixture is stirred at room temperature until gas evolution has ceased. 5-Nitro-2-furaldehyde (0.5 g, 3.5 mmol) is then added and the reaction mixture is stirred at room temperature for 88 h, upon which it is poured on 40 mL of ice-water and extracted 3 times with 60 mL of ethyl acetate. The organic extracts are combined, washed with 150 mL of brine, dried on magnesium sulfate, filtered and concentrated under reduced pressure. The residue is diluted into 50 mL of water and 100 mL of dichloromethane. The aqueous phase is extracted twice with 100 mL of dichloromethane. The organic extracts are combined, washed with 100 mL of water, dried on magnesium sulfate, filtered and concentrated 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 98/2 v/v; rate: 30 mL/min). The fractions containing the desired product are combined and concentrated to dryness under reduced pressure. The residue is taken up in diethyl ether and concentrated to dryness under reduced pressure. 0.28 g of 5-(4,5,6-trifluoro-1H-benzimidazol-2-ylsulfanyl)-furan-2-carbaldehyde is obtained as a pale yellow meringue. mp: 152° C.

1. stirringthe reaction mixture is stirred at room temperature for 88 h, upon which it
2. extractionextracted 3 times with 60 mL of ethyl acetate
3. washwashed with 150 mL of brine
4. customdried on magnesium sulfate
5. filtrationfiltered
6. concentrationconcentrated under reduced pressure
7. additionThe residue is diluted into 50 mL of water and 100 mL of dichloromethane
8. extractionThe aqueous phase is extracted twice with 100 mL of dichloromethane
9. washwashed with 100 mL of water
10. customdried on magnesium sulfate
11. filtrationfiltered
12. concentrationconcentrated under reduced pressure
13. 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 98/2 v/v; rate: 30 mL/min)
14. additionThe fractions containing the desired product
15. concentrationconcentrated to dryness under reduced pressure
16. concentrationconcentrated to dryness under reduced pressure