反应详情

To a solution of freshly prepared lithium diisopropylamide (7.82 mmoles) in 36 ml anhydrous tetrahydrofuran under a nitrogen atmosphere at -75° C. is added a solution of 3-methyl-[1-(t-butyldimethylsilyl)-4-vinyl-2-azetidinone], 24, (1.60 g, 7.11 mmoles) in 10 ml anhydrous THF. The resulting yellow solution of the lithium enolate is, after 16 minutes, treated with excess formaldehyde (see Example 15, below). In 10 minutes, the reaction is quenched by adding 30 ml of a saturated aqueous ammonium chloride solution. This mixture is extracted with 50 ml and 25 ml portions of ethyl acetate. The combined ethyl acetate solutions are washed with 50 ml of brine and dried over anhydrous magnesium sulfate. The drying agent is removed by filtrate is evaporated in vacuo to give the crude product as a yellow oil. Purification by chromatography on silica gel eluting with 10% ethyl acetate/chloroform gives 3-methyl-[1-(t-butyldimethylsilyl)-3-(hydroxymethyl)-4-vinyl-2-azetidinone], 25. ##STR40##

1. customthe reaction is quenched
2. additionby adding 30 ml of a saturated aqueous ammonium chloride solution
3. extractionThis mixture is extracted with 50 ml and 25 ml portions of ethyl acetate
4. washThe combined ethyl acetate solutions are washed with 50 ml of brine
5. dry with materialdried over anhydrous magnesium sulfate
6. customThe drying agent is removed by filtrate
7. customis evaporated in vacuo
8. customto give the crude product as a yellow oil
9. customPurification by chromatography on silica gel eluting with 10% ethyl acetate/chloroform