Hydrochloric Acid → 3-acetoxy-2-methylenehexanoic acid methyl ester

Temperature

2.5 °C

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.

1. temperaturewhile maintaining the temperature at 0-5° C
2. temperatureto warm to room temperature in 1 hour
3. temperaturethe reaction mixture is cooled to 0-5° C. and to it
4. waitin 20 minutes
5. customThe organic layer is separated
6. washwashed sequentially with water (80 ml), saturated aqueous sodium bicarbonate solution (2×80 mL) and water (80 mL)
7. concentrationThe organic layer is concentrated on Rotavap under reduced pressure (20 mbar) until no further solvent
8. distillationdistills

ORD record

ord-c0c52746aadb44908905ee2512cbd077

Source dataset

uspto-grants-2008_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07452999B2