L-Valine → (2S)-2-((methoxycarbonyl)amino)-3-methylbutanoic acid

Temperature

60 °C

To (S)-2-amino-3-methylbutanoic acid (57 g, 487 mmol) dissolved in dioxane (277 mL) was added a 2N aqueous sodium hydroxide solution (803 mL, 1606 mmol) followed by the dropwise addition of methyl chloroformate (75 mL, 973 mmol) over 1 hr which caused warming of the solution to occur. After the addition, the mixture was heated at 60° C. for 22 hrs, then cooled and extracted with dichloromethane (400 mL). The resultant aqueous layer was cooled in an ice bath then 12N hydrochloric acid was added dropwise until the pH was 2. The resultant mixture was stirred at 0° C. for 2 hrs then the resultant solid was vacuum filtered and dried in a vacuum oven to provide 80 g (94%) of the title compound as a colorless solid. 1H NMR (400 MHz, DMSO-d6) δ 12.50 (bs, 1H), 7.34 (d, J=8.6 Hz, 1H), 3.84 (dd, J=8.6, 6.0 Hz, 1H), 3.54 (s, 3H), 2.03 (m, 1H), 0.86 (t, J=7.0 Hz, 6H).

1. temperaturecaused warming of the solution
2. additionAfter the addition
3. temperaturecooled
4. extractionextracted with dichloromethane (400 mL)
5. temperatureThe resultant aqueous layer was cooled in an ice bath
6. addition12N hydrochloric acid was added dropwise until the pH was 2
7. filtrationfiltered
8. customdried in a vacuum oven

ORD record

ord-7c05f75c9b3d4794bc6e001c1dd507d0

Source dataset

uspto-grants-2014_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08691938B2