反应详情

To a mixture of tert-butyl 1-oxa-4,9-diazaspiro[5.5]undecane-9-carboxylate (5.80 g) and dioxane (100 mL), 1 M aqueous sodium hydroxide (24.9 mL) and benzyl chloroformate (3.55 mL) were added sequentially under ice cooling and stirred at room temperature for 16 hours. The reaction mixture was concentrated under reduced pressure and then extracted with ethyl acetate. The organic layer was concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (eluent; n-hexane:ethyl acetate=9:1-1:1) to give 4-benzyl 9-tert-butyl 1-oxa-4,9-diazaspiro[5.5]undecane-4,9-dicarboxylate (8.06 g) as a colorless syrup.

1. additionwere added sequentially under ice cooling
2. concentrationThe reaction mixture was concentrated under reduced pressure
3. extractionextracted with ethyl acetate
4. concentrationThe organic layer was concentrated under reduced pressure
5. customthe residue was purified by silica gel column chromatography (eluent; n-hexane:ethyl acetate=9:1-1:1)