反应详情

38 g (138 mmol) of the compound from Example 14A are dissolved in 200 ml of anhydrous N,N-dimethylformamide, and 12.2 g (198 mmol) of imidazole and, a little at a time, 46 g (135 mmol) of tert-butyl(chloro)diphenylsilane are added at 0° C. The mixture is stirred overnight and then diluted with water and extracted three times with ethyl acetate. The combined organic phases are washed twice with saturated sodium chloride solution, dried over magnesium sulphate, filtered and evaporated under reduced pressure. The residue is applied to silica gel and chromatographed using a gradient of cyclohexane and ethyl acetate. The product-containing fractions are combined and evaporated to dryness under reduced pressure. This gives 62 g (88% of theory) of the desired product.

1. extractionextracted three times with ethyl acetate
2. washThe combined organic phases are washed twice with saturated sodium chloride solution
3. dry with materialdried over magnesium sulphate
4. filtrationfiltered
5. customevaporated under reduced pressure
6. customchromatographed
7. customevaporated to dryness under reduced pressure