反应详情

21 g of the nitrile prepared above according to (a) are dissolved in 100 ml of tetrahydrofuran, a solution of 0.067 mol of lithium diisopropylamide in 100 ml of tetrahydrofuran is then added dropwise at room temperature and the reaction mixture is stirred for one hour at room temperature. 12 g of ethyl bromoacetate are then added and the mixture is heated at 50° C. for two hours. The mixture is cooled, poured into a saturated solution of ammonium chloride and extracted with ethyl ether, the extract is washed with water and the ether phase is separated off by decantation, dried over Na2SO4 and concentrated under vacuum. The residue is purified by chromatography on silica gel using dichloromethane/ethyl acetate (100/1 v/v) as the eluent. Concentration of the pure fractions gives 13 g of the expected compound.

1. temperaturethe mixture is heated at 50° C. for two hours
2. temperatureThe mixture is cooled
3. extractionextracted with ethyl ether
4. washthe extract is washed with water
5. customthe ether phase is separated off by decantation
6. dry with materialdried over Na2SO4
7. concentrationconcentrated under vacuum
8. customThe residue is purified by chromatography on silica gel