Methanol → Ethyl 4-oxobutanoate

Temperature

-60 °C

A solution of ethyl 4-octenoate (34 mL, 173 mmol) in methanol (240 mL) was placed in a 3-neck round bottomed flask and cooled at −60° C., and then O3/O2 was bubbled through the reaction mixture. After 4 hours at ca. −60° C., the reaction mixture had a slight blue tint, and TLC (1:9 ethyl acetate:hexane, stained in phosphomolybdic acid (PMA)) showed no starting material remaining. The reaction mixture was then flushed with O2 for 10 minutes. To the above reaction mixture was added slowly dimethyl sulfide (26 mL, 345 mmol) while maintaining the reaction temperature below −55° C. After the addition was complete, the reaction mixture was allowed to warm to room temperature and stirred overnight. Argon was then bubbled through for 2 hours. The reaction mixture was then concentrated in vacuo. Low pressure fractional distillation afforded 4-oxo-butyric acid ethyl ester (14.3 g, 63%, contained a small amount of dimethyl sulfoxide) as a clear, colorless oil. Alternatively, purification can be accomplished using silica gel chromatography (100% hexanes-20% ethyl acetate in hexane). 1H NMR (300 MHz, CDCl3) δ ppm 9.81 (s, 1 H), 4.14 (q, J=7.2 Hz, 2 H), 2.79 (t, J=6.6 Hz, 2 H), 2.62 (t, J=6.6 Hz, 2 H), 1.26 (t, J=7.2 Hz, 3 H).

1. customO3/O2 was bubbled through the reaction mixture
2. customThe reaction mixture was then flushed with O2 for 10 minutes
3. temperaturewhile maintaining the reaction temperature below −55° C
4. additionAfter the addition
5. temperatureto warm to room temperature
6. customArgon was then bubbled through for 2 hours
7. concentrationThe reaction mixture was then concentrated in vacuo
8. distillationLow pressure fractional distillation

ORD record

ord-eeab2d80810243e8b274705fcb90caba

Source dataset

uspto-grants-2012_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08124629B2