Ethylene Glycol → 2-Methyl-1,3-Dioxolane-2-Carboxylic Acid

Temperatur

40 °C

To a stirred mixture containing ethyl pyruvate (11.1 mL, 0.1 mol) and ethylene glycol (5.6 mL, 0.1 mol) in anhydrous dichloromethane (100 mL) at 0° C. was added boron trifluoride dietherate (6.4 mL, 0.05 mol) and catalytic amount of acetic acid. The resulting mixture was stirred at 40° C. for 16 h and then diluted with 100 mL of dichloromethane. The organic solution was washed successively with saturated sodium chloride solution (2×80 mL). The organic layer was separated and the combined organic extracts were concentrated. The residue was treated with 1N sodium hydroxide at room temperature. After stirring at room temperature for 3 h (monitored by TLC), citric acid was added to adjust the pH to 4. The product was extracted with dichloromethane, dried over Na2SO4 and concentrated to afford 5.1 g (38%) of the title compound (129) as a clear liquid. This material was used in the next reaction without further purification. 1H NMR (CDCl3, 400 MHz): δ 1.55 (s, 3H), 4.03 (m, 4H).

1. washThe organic solution was washed successively with saturated sodium chloride solution (2×80 mL)
2. customThe organic layer was separated
3. concentrationthe combined organic extracts were concentrated
4. additionThe residue was treated with 1N sodium hydroxide at room temperature
5. stirringAfter stirring at room temperature for 3 h (monitored by TLC), citric acid
6. additionwas added
7. extractionThe product was extracted with dichloromethane
8. dry with materialdried over Na2SO4
9. concentrationconcentrated

ORD-Eintrag

ord-fe6c6cf96de94936859166b3addb09ea

Quelldatensatz

uspto-grants-2004_11

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US06818787B2