反应详情

A mixture of tert-butyl (S)-4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)piperazine-1-carboxylate prepared in Example 393 (1.87 g, 5.09 mmol) and methylene chloride (20 ml) was added trifluoroacetic acid (20 ml) followed by stirring for 5 minutes, and then concentrated under reduced pressure. The residue was dissolved in DMF (20 ml). To the solution, a mixture of 1,1′-carbonyldiimidazole (1.76 g, 10.9 mmol), 4-(trifluoromethyl)benzyl alcohol (1.92 g, 10.9 mmol) and DMF (20 ml) stirred at room temperature for 3 hours was added followed by stirring at room temperature overnight. The reaction mixture was extracted with ethyl acetate. The organic phases were combined, washed with water and a saturated saline solution, dried over sodium sulfate and then filtered. The resulting filtrate was concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (n-hexane/acetone=3/1), recrystallized from isopropyl alcohol. The resulting solids were filtered off and then dried under reduced pressure to afford 4-trifluoromethylbenzyl (S)-4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)piperazine-1-carboxylate (1.48 g, yield 53%) as a light yellow powder.

1. concentrationconcentrated under reduced pressure
2. dissolutionThe residue was dissolved in DMF (20 ml)
3. stirringstirred at room temperature for 3 hours
4. additionwas added
5. stirringby stirring at room temperature overnight
6. extractionThe reaction mixture was extracted with ethyl acetate
7. washwashed with water
8. dry with materiala saturated saline solution, dried over sodium sulfate
9. filtrationfiltered
10. concentrationThe resulting filtrate was concentrated under reduced pressure
11. customthe residue was purified by silica gel column chromatography (n-hexane/acetone=3/1)
12. customrecrystallized from isopropyl alcohol
13. filtrationThe resulting solids were filtered off
14. customdried under reduced pressure