Diethyl Oxalate → 3-(2-Methyl-5-nitropyridin-4-yl)-2-oxopropionic acid ethyl ester

To a solution of potassium ethoxide (0.262 g, 2.96 mmol) in diethyl ether (10 mL) and ethanol (1 mL) was added diethyl oxalate (0.404 mL, 2.96 mmol) in one portion and the resulting solution stirred for 10 min at rt. 2,4-Dimethyl-5-nitropyridine (Preparation 63, 0.400 g, 2.63 mmol) was added as a suspension in diethyl ether (1 mL)/ethanol (1.5 mL) and stirring continued for 16 h at rt. The mixture was filtered, washing with cold diethyl ether. The collected precipitate was dissolved in water and the pH adjusted to 4 by the addition of glacial acetic acid. The resulting precipitate was collected by filtration and air dried. The solid was partitioned between ethyl acetate (150 mL) and water (50 mL) and the layers separated. The aqueous layer was extracted with ethyl acetate (3×20 mL) and the combined organics washed with brine (50 mL), dried (MgSO4), filtered and concentrated under reduced pressure to give the title compound as a red solid which required no further purification. δH (CDCl3): 1.40 (3H, t), 4.40 (2H, q), 4.52 (2H, s), 7.11 (1H, s), 9.25 (1H, s).

1. stirringstirring
2. waitcontinued for 16 h at rt
3. filtrationThe mixture was filtered
4. washwashing with cold diethyl ether
5. dissolutionThe collected precipitate was dissolved in water
6. additionthe pH adjusted to 4 by the addition of glacial acetic acid
7. filtrationThe resulting precipitate was collected by filtration and air
8. customdried
9. customThe solid was partitioned between ethyl acetate (150 mL) and water (50 mL)
10. customthe layers separated
11. extractionThe aqueous layer was extracted with ethyl acetate (3×20 mL)
12. washthe combined organics washed with brine (50 mL)
13. dry with materialdried (MgSO4)
14. filtrationfiltered
15. concentrationconcentrated under reduced pressure

ORD-Eintrag

ord-7edb535ba4454dc1af7cec6ecdb4529c

Quelldatensatz

uspto-grants-2008_07

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US07405210B2