反应详情

To a solution of hexamethyldisilazane (4.3 mL, 20 mmole) in tetrahydrofuran (5 mL) at 0° C. was added n-butyllithium (8.4 mL of 2.5M, 21 mmole) dropwise. The mixture was allowed to warm to room temperature for 20 minutes and then recooled to 0° C. In a separate flask, the product of Step B (3.0 g, 17 mmole) in tetrahydrofuran (10 mL) was cooled to 0° C. The lithiohexamethyldisilazane solution was added via cannula to the aldehyde solution. The reaction mixture was warmed to 22° C. for 20 minutes and then ethyl magnesium bromide (14 mL of 3.0M, 42 mmole) was added dropwise. After heating the mixture at reflux for 12 hours, it was cooled and quenched with saturated aqueous ammonium chloride solution. The aqueous phase was separated and extracted with ether. Combination of the organic phases, drying (MgSO4), and concentration gave a crude residue which was chromatographed on silica gel with ethyl acetate. The desired product was obtained as a colorless oil (0.95 g, 27% yield).

1. customrecooled to 0° C
2. temperatureThe reaction mixture was warmed to 22° C. for 20 minutes
3. temperatureAfter heating the mixture
4. temperatureat reflux for 12 hours
5. temperatureit was cooled
6. customquenched with saturated aqueous ammonium chloride solution
7. customThe aqueous phase was separated
8. extractionextracted with ether
9. customCombination of the organic phases, drying
10. concentration(MgSO4), and concentration
11. customgave a crude residue which
12. customwas chromatographed on silica gel with ethyl acetate