反应详情

Aldehyde intermediate preparation: 5-Chloro-2-mercaptobenzimidazole (1.5 g, 8.12 mmol) dissolved in 10 ml of anhydrous tetrahydrofuran is added dropwise to a suspension of sodium hydride (60% dispersion in mineral oil, 0.325 g, 8.12 mmol) in anhydrous tetrahydrofuran (20 ml) at 10° C. over a 15 minute period. The reaction mixture is stirred for 2 hours at room temperature. Then 5-nitro-2-furaldehyde (1.146 g, 8.12 mmol) dissolved in 20 ml of anhydrous tetrahydrofuran is added dropwise over a 15 minute period and the reaction mixture is stirred at room temperature for an additional 16 hour period. The reaction mixture is then poured into 300 ml of water and extracted twice with 150 ml of ethyl acetate. The combined organic extracts are dried over MgSO4 and concentrated under reduced pressure. The residue is purified on a silica gel column (120 g) eluted with a mixture of cyclohexane and ethyl acetate (80/20, v/v) to yield 1.9 g of 5-(6-chloro-1H-benzimidazol-2-ylsulfanyl)-furan-2-carbaldehyde. Yield=88%. Analytical LC/MS (method B): retention time=3.40 min., m/z=278.95/1Cl (positive ion mode).

1. additionis added dropwise over a 15 minute period
2. stirringthe reaction mixture is stirred at room temperature for an additional 16 hour period
3. extractionextracted twice with 150 ml of ethyl acetate
4. dry with materialThe combined organic extracts are dried over MgSO4
5. concentrationconcentrated under reduced pressure
6. customThe residue is purified on a silica gel column (120 g)
7. washeluted with a mixture of cyclohexane and ethyl acetate (80/20