反应详情

To stannous chloride (379 mg) was added a dichloromethane solution (10 ml) of chlorotrimethylsilane (217 mg) followed by addition of a dichloromethane solution (10 ml) of (3R,4R)-4-acetoxy-3-[(R)-1-[(tert-butyldimethylsilyl)oxy]ethyl]-1-trimethylsilylazetidin-2-one (7.19 g). To this suspension was added a dichloromethane solution (10 ml) of 2-[(trimethylsilyl)oxy]-1,3-cyclohexadiene (4.05 g) dropwise at room temperature over a period of 1 hour. The mixture was stirred at 25° C. for 2 hours, at the end of which time a dichloromethane solution (10 ml) of 2-[(trimethylsilyl)oxy]-1,3-cyclohexadiene (5.38 g) was added dropwise over a period of 1 hour. The mixture was further stirred for 5 hours and then allowed to stand at 0° C. overnight. The solvent was then distilled off under reduced pressure. To the residue were added ether (100 ml) and aqueous sodium hydrogen carbonate solution (30 ml) and the mixture was stirred for 10 minutes. The insolubles were filtered off and the aqueous layer was extracted with ether. The ether layer was washed with saturated aqueous sodium chloride solution and dried over anhydrous sodium sulfate. The solvent was then distilled off under reduced pressure and the residue was dissolved in THF-water (17:2, 95 ml). To this solution was added pyridinium p-toluenesulfonate (610 mg) and the mixture was stirred at room temperature for 1 hour. The solvent was distilled off under reduced pressure and ether (150 ml) was added to the residue. The organic layer was washed successively with water and saturated sodium chloride solution and dried over anhydrous sodium sulfate. The solvent was then distilled off under reduced pressure and the residue was purified by flash column chromatography (packing: silica gel 300 g; ether-hexane 5:1) to give (3S,4R)-3-[(R)-1-[(tert-butyldimethylsilyl)oxy]ethyl]-4-[(R)-2-oxo-3-cyclohexen-1-yl]azetiidin-2-one (R-compound; 1.01 g) and (3S,4R)-3-[(R)-1-[(tert-butyldimethylsilyl)oxy]ethyl]-4-[(S)-2-oxo-3-cyclohexen-1-yl]azetidin-2-one (S-compound; 0.96 g).

1. additionwas added dropwise over a period of 1 hour
2. waitto stand at 0° C. overnight
3. distillationThe solvent was then distilled off under reduced pressure
4. additionTo the residue were added ether (100 ml) and aqueous sodium hydrogen carbonate solution (30 ml)
5. stirringthe mixture was stirred for 10 minutes
6. filtrationThe insolubles were filtered off
7. extractionthe aqueous layer was extracted with ether
8. washThe ether layer was washed with saturated aqueous sodium chloride solution
9. dry with materialdried over anhydrous sodium sulfate
10. distillationThe solvent was then distilled off under reduced pressure
11. dissolutionthe residue was dissolved in THF-water (17:2, 95 ml)
12. additionTo this solution was added pyridinium p-toluenesulfonate (610 mg)
13. stirringthe mixture was stirred at room temperature for 1 hour
14. distillationThe solvent was distilled off under reduced pressure and ether (150 ml)
15. additionwas added to the residue
16. washThe organic layer was washed successively with water and saturated sodium chloride solution
17. dry with materialdried over anhydrous sodium sulfate
18. distillationThe solvent was then distilled off under reduced pressure
19. customthe residue was purified by flash column chromatography (packing: silica gel 300 g; ether-hexane 5:1)