反应详情

2,4-Dinitro-1H-imidazole (1.0 g, 6.3 mmol), tert-butyl 1-oxa-6-azaspiro[2,5]octane-6-carboxylate (2.0 g, 9.5 mmol) and sodium acetate (612 mg, 7.5 mmol) in ethanol (7 ml) were stirred under reflux for 10 hours. The reaction mixture was concentrated under reduced pressure. To the residue, a saturated sodium hydrogencarbonate solution and methylene chloride were added followed by stirring vigorously, and then the mixture was extracted with methylene chloride. The organic phase was dried over sodium sulfate and then filtered. The resulting filtrate was concentrated under reduced pressure, and the residue was crystallized from methylene chloride-diisopropyl ether to afford 1′-tert-butoxycarbonyl-2,3-dihydro-6-nitrospiro[imidazo[2,1-b]oxazole-2,4′-piperidine] (586 mg, yield 29%) as a white powder.

1. temperatureunder reflux for 10 hours
2. concentrationThe reaction mixture was concentrated under reduced pressure
3. additionTo the residue, a saturated sodium hydrogencarbonate solution and methylene chloride were added
4. extractionthe mixture was extracted with methylene chloride
5. dry with materialThe organic phase was dried over sodium sulfate
6. filtrationfiltered
7. concentrationThe resulting filtrate was concentrated under reduced pressure
8. customthe residue was crystallized from methylene chloride-diisopropyl ether