反应详情

In accordance with the process disclosed in Tetrahedron, 35, 551 (1979), 2-acetyl-3-bromofuran (10.0 g, 53.2 mmol) and carbon disulfide (7.0 g, 93.2 mmol) were dissolved in anhydrous dimethylformamide (70 ml) and the solution was added with 55% sodium hydride (4.0 g, 93.2 mmol) over about 1.5 hours while it was stirred and inner temperature was maintained below 10° C. under ice cooling. After further stirring for 0.5 hour at the temperature, the solution was added with methanol (1.1 ml, 26.6 mmol) and further stirred at room teperature for 40 minutes. Then, the solution was heated and stirred in the boiling water bath for 1 hour and allowed to cool to room temperature. Under water cooling, the solution was added dropwise with methyl iodide (22.6 g, 159.6 mmol) and stirred at room temperature for 24 hours. The solution was injected into ice water, extracted with dichloromethane (300 ml×2 times), washed with water and dried over anhydrous magnesium sulfate. The solvent was removed under reduced pressure and the residue was recrystallized from ethanol using active carbon to obtain 5.9 g (yield: 56%) of 5-methylthio-7-oxo-7H-thiopyrano[3,2-b]furan as colorless needles.

1. temperatureinner temperature was maintained below 10° C. under ice cooling
2. stirringAfter further stirring for 0.5 hour at the temperature
3. stirringfurther stirred at room teperature for 40 minutes
4. temperatureThen, the solution was heated
5. stirringstirred at room temperature for 24 hours
6. extractionextracted with dichloromethane (300 ml×2 times)
7. washwashed with water
8. dry with materialdried over anhydrous magnesium sulfate
9. customThe solvent was removed under reduced pressure
10. customthe residue was recrystallized from ethanol using active carbon