Acetic Acid → HCID 59752195, compound

Temperature

0 °C

A solution of 1.74 mL (12.4 mmol) of diisopropylamine in 20 mL of tetrahydrofuran was cooled to −78° C. before 7.75 mL (12.4 mmol) of 1.6 M n-butyl lithium in hexanes was added dropwise. The solution was allowed to warm to 0° C. briefly before being cooled to −78° C. A solution of dimethyl (2S,3S)-2-hydroxy-3-methylbutanedioate in 1 mL of tetrahydrofuran was then added dropwise. The reaction mixture was allowed to warm to −10° C., and was stirred for 45 min before being cooled to −78° C. To the reaction mixture was added 0.52 mL (6.5 mmol) of ethyl iodide dropwise. The reaction mixture was then stirred for 1 h before being allowed to warm to room temperature. After 18 h, the reaction mixture was poured onto a mixture of ether, ice water, and 1.8 mL of acetic acid. The mixture was extracted with ether, and the combined extracts were washed with saturated sodium bicarbonate and brine, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica chromatography eluting with 3:7 ethyl acetate:hexanes to afford 430 mg (6.8%) of dimethyl (2R,3S)-2-ethyl-3-hydroxy-2-methylbutanedioate. 1H NMR (300 MHz, DMSO-d6) δ 5.73 (s, 1H), 4.28 (s, 1H), 3.66 (s, 3H), 3.62 (s, 3H), 1.66 (m, 1H), 1.38 (m, 1H), 0.76 (t, J=7 Hz, 3H).

1. additionwas added dropwise
2. temperaturebefore being cooled to −78° C
3. temperatureto warm to −10° C.
4. temperaturebefore being cooled to −78° C
5. stirringThe reaction mixture was then stirred for 1 h
6. temperatureto warm to room temperature
7. waitAfter 18 h
8. extractionThe mixture was extracted with ether
9. washthe combined extracts were washed with saturated sodium bicarbonate and brine
10. dry with materialdried over magnesium sulfate
11. concentrationconcentrated under reduced pressure
12. customThe residue was purified by silica chromatography
13. washeluting with 3:7 ethyl acetate

ORD record

ord-e12a575f7d02455d8044dec213f370b1

Source dataset

uspto-grants-2008_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07402606B2