反应详情

To a solution of 500 mg of 3-{(2R)-2-[(3S, 4R)-3-[(1R)-1-t-butyldimethylsilyloxyethyl]-2-oxoazetidin-4-yl]propionyl}-spiro[2,3-dihydro-4H-1,3-benzoxazine-2,1'-cyclohexan]-4-one in 20 ml of a mixture of tetrahydrofuran and water are added 0.9 ml of 30% aqueous hydrogen peroxide and 84 mg of lithium hydroxide in this order, and the mixture is stirred at the same temperature for one hour. The pH of the mixture is adjusted to about 10 by adding dropwise 5 ml of 1.5N aqueous sodium sulfite at the same temperature and tetrahydrofuran is removed under reduced pressure. The precipitated crystals are removed by filtration and the aqueous layer of the filtrate is washed with 20 ml of chloroform. 10 ml of 10% hydrochloric acid are added thereto and the pH of the mixture is adjusted to about one. The aqueous layer is extracted with 30 ml of ethyl acetate. The ethyl acetate layer is dried and then evaporated under reduced pressure to give the crude product. The product is recrystallized from a mixture of ethyl acetate and hexane to obtain 216 mg of (2R)-2-[(3S, 4R)-3-[(1R)-1-t-butyldimethylsilyloxyethyl]-2-oxoazetidin-4-yl]propionic acid.

1. customis removed under reduced pressure
2. customThe precipitated crystals are removed by filtration
3. washthe aqueous layer of the filtrate is washed with 20 ml of chloroform
4. addition10 ml of 10% hydrochloric acid are added
5. extractionThe aqueous layer is extracted with 30 ml of ethyl acetate
6. dry with materialThe ethyl acetate layer is dried
7. customevaporated under reduced pressure
8. customto give the crude product
9. customThe product is recrystallized from a mixture of ethyl acetate and hexane