反应详情

In a nitrogen stream under stirring, 50 ml of dry tetrahydrofuran is cooled to -78° C. and, then, 20 ml of a solution of 15% n-butyllithium in n-hexane is added thereto. After dropwise addition of 3.66 ml of diisopropylamine, the mixture is stirred at -78° C. for 15 minutes. A solution of 3.1 g of 2,2-dimethyl-1-aza-3-oxabicyclo[4.2.0]octan-8-one in 15 ml of dry tetrahydrofuran is added dropwise and the mixture is stirred at -78° C. for one hour. Then, a solution of 4.34 g of p-toluenesulfonyl azide in 15 ml of dry tetrahydrofuran is added dropwise and the mixture is stirred at -50° C. to -60° C. for 1.5 hours. To this mixture 5.1 ml of trimethylsilyl chloride is added dropwise and the reaction mixture is heated under reflux for 5 hours. After cooling, the insolubles are filtered off and the filtrate is concentrated under reduced pressure. The residue is shaken with water and ethyl acetate and the ethyl acetate layer is separated, washed with water, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The solvent is then distilled off and the residue is purified by silica gel column chromatography to give 2,2-dimethyl-7-azido-1-aza-3-oxabicyclo[4.2.0]octan-8-one as a 1:4 mixture of cis- and trans-isomers.

1. stirringthe mixture is stirred at -78° C. for 15 minutes
2. stirringthe mixture is stirred at -78° C. for one hour
3. stirringthe mixture is stirred at -50° C. to -60° C. for 1.5 hours
4. temperaturethe reaction mixture is heated
5. temperatureunder reflux for 5 hours
6. temperatureAfter cooling
7. filtrationthe insolubles are filtered off
8. concentrationthe filtrate is concentrated under reduced pressure
9. stirringThe residue is shaken with water and ethyl acetate
10. customthe ethyl acetate layer is separated
11. washwashed with water
12. dry with materialdried over anhydrous sodium sulfate
13. concentrationconcentrated under reduced pressure
14. distillationThe solvent is then distilled off
15. customthe residue is purified by silica gel column chromatography