Acetic Acid → Ethyl 2-methyl-4-oxocyclopent-2-ene-1-carboxylate

In a 5 L round bottom flask, sodium 4-(ethoxycarbonyl)-2-(methoxycarbonyl)-3-methylcyclo-penta-1,3-dienolate (485 g, 1954 mmol), KCl (204 g, 2736 mmol, JT Baker), and AcOH (392 mL, 6839 mmol, JT Baker) in toluene (1200 mL) and water (1200 mL) were heated at reflux for about 6 h. The reaction mixture was allowed to cool to ambient temperature for about 16 h. The reaction mixture was then poured into a 12 L flask and diluted with water (3 L). Solid NaHCO3 (450 g, 5.3 mol) was added cautiously portionwise with stirring over about 1 h. After about an additional 30 min of stirring, the basic aqueous phase was separated and further extracted with Et2O (4×400 mL). The combined organic layers were washed with water (4×500 mL) and brine (500 mL), dried over anhydrous MgSO4, filtered, and concd under reduced pressure to yield a yellow oil that was purified by vacuum distillation (92-94° C., 0.4 mmHg) to give ethyl 2-methyl-4-oxocyclopent-2-enecarboxylate (229 g, 69%) as a yellow oil: 1H NMR (CDCl3) δ 6.04-6.01 (m, 1H), 4.26-4.17 (m, 2H), 3.67 (m, 1H), 2.72 (m, 1H), 2.62 (m, 1H), 2.16 (s, 3H), 1.32-1.27 (t, J=7.1 Hz, 3H).

1. temperatureat reflux for about 6 h
2. additionThe reaction mixture was then poured into a 12 L flask
3. stirringAfter about an additional 30 min of stirring
4. customthe basic aqueous phase was separated
5. extractionfurther extracted with Et2O (4×400 mL)
6. washThe combined organic layers were washed with water (4×500 mL) and brine (500 mL)
7. dry with materialdried over anhydrous MgSO4
8. filtrationfiltered
9. customconcd under reduced pressure to yield a yellow oil that
10. distillationwas purified by vacuum distillation (92-94° C., 0.4 mmHg)

ORD record

ord-c9d4b36f85db4d40a8dd7b17ad59d47b

Source dataset

uspto-grants-2013_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08426411B2