反应详情

Potassium thiocyanate (6.44 g, 66 mmol) is suspended in 18 ml of methanol and cooled to -78° under nitrogen. A solution of 1.75 ml of bromine (33 mmol) in 10 ml methanol is added dropwise. The resulting light yellow suspension is stirred for an additional 5 minutes at -78° before 4.17 g (30 mmole) of 2-methoxycarbonyl-1-methylpyrrole in 5 ml methanol is added all at once. After stirring and gradual warming to room temperature, the reaction mixture is poured into 250 ml of ice water, stirred vigorously and filtered. The solid is washed with water, dissolved in methylene chloride, dried over anhydrous sodium sulfate, and concentrated in vacuo to give a white solid which after recrystallization from hexane-ethyl acetate gives 2.8 g of pure 4-cyanothio-2-methoxycarbonyl-1-methylpyrrole.

1. temperaturecooled to -78° under nitrogen
2. additionis added all at once
3. stirringstirred vigorously
4. filtrationfiltered
5. washThe solid is washed with water
6. dissolutiondissolved in methylene chloride
7. dry with materialdried over anhydrous sodium sulfate
8. concentrationconcentrated in vacuo
9. customto give a white solid which
10. customafter recrystallization from hexane-ethyl acetate