反应详情

温度

40 °C

2,5,6-Trichlorobenzimidazole (221 mg, 1.0 mmol) was suspended in acetonitrile (15 ml) and the mixture was stirred at 40° C. BSA (365 μl, 1.5 mmol) was added, and the reaction mixture stirred for 15 min. A solution of 3 (260 mg, 1.0 mmol) in acetonitrile (5 ml) and TMSOTf (290 μl, 1.5 mmol) was added to the clear solution, and the mixture was allowed to stand at room temperature for 18 hours. The mixture was concentrated under reduced pressure, and the residue was dissolved with dichloromethane (50 ml). The solution was washed with a saturated aqueous solution of sodium bicarbonate (10 ml) and with water (3×10 ml), dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The residue was taken up with the minimum amount of dichloromethane and chromatographed on a silica gel column (eluent: gradient of methanol (0-1.6%) in dichloromethane). Fractions having a UV-absorbing spot that also charred under H2SO4 and heating were pooled and concentrated to a foam which was dissolved in ethanol 90 (11 ml). To the stirred solution was added sodium carbonate (216 mg, 2.0 mmol) and the reaction mixture was stirred overnight. The mixture was then evaporated under reduced pressure, dissolved in a 2:1 mixture of ethyl acetate and dichloromethane, and washed with water. The organic layer was dried over sodium sulfate, filtered and evaporated under reduced pressure. Compound 4 crystallized from a 2% methanolic solution of dichloromethane (120 mg, 56%).

1. additionBSA (365 μl, 1.5 mmol) was added
2. stirringthe reaction mixture stirred for 15 min
3. concentrationThe mixture was concentrated under reduced pressure
4. dissolutionthe residue was dissolved with dichloromethane (50 ml)
5. washThe solution was washed with a saturated aqueous solution of sodium bicarbonate (10 ml) and with water (3×10 ml)
6. dry with materialdried over anhydrous sodium sulfate
7. filtrationfiltered
8. concentrationconcentrated under reduced pressure
9. customchromatographed on a silica gel column (eluent: gradient of methanol (0-1.6%) in dichloromethane)
10. temperatureheating
11. concentrationconcentrated to a foam which
12. dissolutionwas dissolved in ethanol 90 (11 ml)
13. stirringthe reaction mixture was stirred overnight
14. customThe mixture was then evaporated under reduced pressure
15. dissolutiondissolved in a 2:1 mixture of ethyl acetate and dichloromethane
16. washwashed with water
17. dry with materialThe organic layer was dried over sodium sulfate
18. filtrationfiltered
19. customevaporated under reduced pressure
20. customCompound 4 crystallized from a 2% methanolic solution of dichloromethane (120 mg, 56%)