[O:1]=[C:2]([CH3:11])[CH2:3][C:4]([O:6][C:7]([CH3:10])([CH3:9])[CH3:8])=[O:5].[H-].[Na+].I[CH2:15][CH2:16][CH2:17][CH2:18][C:19]([O:21][CH2:22][CH3:23])=[O:20]>O1CCCC1>[C:2]([CH:3]([CH2:15][CH2:16][CH2:17][CH2:18][C:19]([O:21][CH2:22][CH3:23])=[O:20])[C:4]([O:6][C:7]([CH3:10])([CH3:9])[CH3:8])=[O:5])(=[O:1])[CH3:11]To a solution of tert-butyl 3-oxobutanoate (20.0 g) in tetrahydrofuran (200 mL) was added 60% sodium hydride in oil (556 g) portionwise over 20 minutes in an ice-water bath under N2. After 40 minutes, to the mixture was added ethyl 5-iodopentanoate (35.6 g) at the temperature. After 15 minutes, the mixture was stirred at ambient temperature. After 1 hour, the reaction mixture was heated at 50° C. for 24 hours. The cooled mixture was partitioned between ethyl acetate and water. The aqueous layer was extracted with ethyl acetate. The combined organic layer was washed with water and brine, dried over magnesium sulfate, and evaporated in vacuo. The residue was purified by flash silica gel chromatography (silica gel, 1 L) eluting with hexane-ethyl acetate=50-1, 20-1, 10-1, and 8-1 to give 1-tert-butyl 7-ethyl 2-acetylheptanedioate (27.3 g, 75.4%) as colorless oil.
Wird geladen…
