[CH2:1]([O:3][C:4]([C:6]1[CH2:10][C:9]([O-:11])=[C:8](C(OC)=O)[C:7]=1[CH2:16][CH3:17])=[O:5])[CH3:2].[Na+].[Cl-].[K+].CC(O)=O.C([O-])(O)=O.[Na+]>O.C1(C)C=CC=CC=1>[CH2:16]([C:7]1[CH:6]([C:4]([O:3][CH2:1][CH3:2])=[O:5])[CH2:10][C:9](=[O:11])[CH:8]=1)[CH3:17]
A 5 L round bottom flask was charged with sodium 4-(ethoxycarbonyl)-3-ethyl-2-(methoxycarbonyl)cyclopenta-1,3-dienolate (316 g, 1205 mmol), KCl (126 g, 1687 mmol, JT-Baker), AcOH (241 mL, 4218 mmol, JT-Baker), toluene (1850 mL) and water (130 mL). The reaction was heated at reflux for about 6 h then cooled to ambient temperature and added dropwise to NaHCO3 (8% w/v aqueous, 3.5 L). The resulting biphasic mixture was extracted with MTBE (2×1.5 L). The combined organic layers were washed with brine (1 L), dried over anhydrous MgSO4 and concd under reduced pressure to give 191 g of crude material that was purified by vacuum distillation (97-99° C., 0.600 mm Hg) to give ethyl 2-ethyl-4-oxocyclopent-2-enecarboxylate (160 g, 69%): 1H NMR (CDCl3) δ 6.04 (m, 1H), 4.26-4.15 (m, 2H), 3.76-3.69 (m, 1H), 2.75-2.57 (m, 2H), 2.56-2.44 (m, 2H), 1.32-1.26 (m, 3H), 1.23-1.18 (m, 3H).
Wird geladen…
