[CH3:1][O:2][C:3](=[O:11])[C:4](=[CH2:10])[CH:5]([OH:9])[CH2:6][CH2:7][CH3:8].[C:12](OC(=O)C)(=[O:14])[CH3:13].Cl>CN(C1C=CN=CC=1)C.C1(C)C=CC=CC=1>[CH3:1][O:2][C:3](=[O:11])[C:4](=[CH2:10])[CH:5]([O:9][C:12](=[O:14])[CH3:13])[CH2:6][CH2:7][CH3:8]A mixture of 3-hydroxy-2-methylenehexanoic acid methyl ester (55.37 g, 350 mmol) and DMAP (4.28 g, 35 mmol) in toluene (400 mL) is cooled to 0-5° C. and to it is added acetic anhydride (42.88 g, 420 mmol) dropwise in ˜30 minutes while maintaining the temperature at 0-5° C. The resulting solution is allowed to warm to room temperature in 1 hour. After stirring for 3 hours at RT, the reaction mixture is cooled to 0-5° C. and to it is added 1 N HCl acid (80 mL), in 20 minutes. The organic layer is separated and washed sequentially with water (80 ml), saturated aqueous sodium bicarbonate solution (2×80 mL) and water (80 mL). The organic layer is concentrated on Rotavap under reduced pressure (20 mbar) until no further solvent distills to afford 3-acetoxy-2-methylenehexanoic acid methyl ester (68.39 g, yield: 97.5%) as a colorless liquid.
Wird geladen…
