Ethanol → (5R,9R)-2-acetyl-5,9,13-trimethyltetradecanoic acid ethyl ester
Reaktionsgleichung
[CH2:1]([O:3][C:4](=[O:6])[CH3:5])[CH3:2].Br[CH2:8][CH2:9][C@H:10]([CH3:22])[CH2:11][CH2:12][CH2:13][C@H:14]([CH3:21])[CH2:15][CH2:16][CH2:17][CH:18]([CH3:20])[CH3:19].[CH2:23]([OH:25])[CH3:24]>>[CH2:1]([O:3][C:4](=[O:6])[CH:5]([C:23](=[O:25])[CH3:24])[CH2:8][CH2:9][C@H:10]([CH3:22])[CH2:11][CH2:12][CH2:13][C@H:14]([CH3:21])[CH2:15][CH2:16][CH2:17][CH:18]([CH3:20])[CH3:19])[CH3:2]Komponenten
4
Versuchsvorschrift
To 2.3 ml of a solution of 1.01-N sodium ethylate in ethanol in a flask provided with reflux condenser and calcium chloride tube are added dropwise 300 mg (2.3 mmol) of acetic acid ethyl ester and subsequently 671 mg (2.3 mmol) of (3R,7R)-1-bromo-3,7,11-trimethyldodecane in 2 ml of ethanol. This mixture is boiled under reflux for 15 hours while stirring. After cooling, so much ice water is added that the separated salt is just dissolved, the organic phase is separated in a separating funnel and shaken out four times with methylene chloride. After drying the combined organic phases over magnesium sulphate and distillation of the solvent, there are obtained 755 mg of crude (5R,9R)-2-acetyl-5,9,13-trimethyltetradecanoic acid ethyl ester. For analytical purposes a sample of the crude (5R,9R)-2-acetyl-5,9,13-trimethyl-tetradecanoic acid ethyl ester is chromatographed on a preparative silicagel plate with toluene/hexane/acetic acid ethyl ester = 30:10:3 and the thus obtained pure (5R,9R)-2-acetyl-5,9,13-trimethyl-tetradecanoic acid ethyl ester is distilled at 150°/0.03 Torr; [α]36520 = -4.0° (c = 1.04; CHCl3).