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 (300 mg, 0.82 mmol) and trifluoroacetic acid (6 ml) was stirred at room temperature for 3 hours. The reaction mixture was concentrated under reduced pressure. The residue was dissolved in methylene chloride (15 ml), and the solution was added triethylamine (2 ml, 14.35 mmol). To the solution, 4-chlorobenzoyl chloride (150.7 mg, 0.86 mmol) was added with cooling on ice-bath followed by stirring at room temperature for 1 hour. The reaction mixture was washed with a saturated sodium hydrogencarbonate solution, water and a saturated saline solution in this order, dried over sodium sulfate and then filtered. The filtrate was concentrated under reduced pressure, and the residue was treated with diethyl ether-ethyl acetate to afford (S)-(4-chlorophenyl)-[4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethyl)piperazin-1-yl]methanone (282 mg, yield 85%) as a yellow powder.

1. concentrationThe reaction mixture was concentrated under reduced pressure
2. dissolutionThe residue was dissolved in methylene chloride (15 ml)
3. temperaturewith cooling on ice-bath
4. stirringby stirring at room temperature for 1 hour
5. washThe reaction mixture was washed with a saturated sodium hydrogencarbonate solution, water
6. dry with materiala saturated saline solution in this order, dried over sodium sulfate
7. filtrationfiltered
8. concentrationThe filtrate was concentrated under reduced pressure
9. additionthe residue was treated with diethyl ether-ethyl acetate