反应详情

4-Chlorophenylisocyanate (169 ml, 1.1 mmol) and cuprous chloride (50 mg, 0.5 mmol) was added to a solution of 2-hydroxyethyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazole prepared in Example 31 (0.2 g, 1.0 mmol) in DMF (5 ml) with cooling on ice-bath followed by stirring at room temperature for 4 hours. The mixture was cooled on ice-bath and added 10% hydrochloric acid. The resulting mixture was extracted with ethyl acetate, and the extract was washed with water, dried over magnesium sulfate, and then concentrated under reduced pressure. The residue was purified by silica gel column chromatography (methylene chloride/methanol=100/1) and crystallized from methylene chloride-isopropyl ether to afford 2-(6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-yl)ethyl 4-chlorophenylcarbamate (0.16 g, yield 45%) as a white solid.

1. temperaturewith cooling on ice-bath
2. temperatureThe mixture was cooled on ice-bath
3. extractionThe resulting mixture was extracted with ethyl acetate
4. washthe extract was washed with water
5. dry with materialdried over magnesium sulfate
6. concentrationconcentrated under reduced pressure
7. customThe residue was purified by silica gel column chromatography (methylene chloride/methanol=100/1)
8. customcrystallized from methylene chloride-isopropyl ether