Furan → Ethyl 7-oxabicyclo[2.2.1]hept-5-ene-2-carboxylate
Reaktionsgleichung
[O:1]1[CH:5]=[CH:4][CH:3]=[CH:2]1.[C:6]([O:10][CH2:11][CH3:12])(=[O:9])[CH:7]=[CH2:8]>[Cl-].[Zn+2].[Cl-]>[CH2:11]([O:10][C:6]([CH:7]1[CH2:8][CH:2]2[O:1][CH:5]1[CH:4]=[CH:3]2)=[O:9])[CH3:12]Komponenten
4
Edukt 2
Produkt 1
Reagenzien, Katalysatoren, Lösungsmittel 1
Reaktionsbedingungen
- Temperatur
- 3 °C
Versuchsvorschrift
A mixture of 300 g of furan (4.32 mol) and 611 g (6.05 mol) of ethyl acrylate was cooled to 3° C. in an ice bath under an inert atmosphere. 706 g (5.2 mol) of zinc chloride were added portionwise to the solution during 30 min, maintaining the temperature at between 10° C. and 20° C. After completed addition, the cooling bath was removed and the mixture was allowed to gradually heat up during 30 min to 50° C. by exothermy. It was subsequently kept at 50° C. during 27 h by means of an oil bath, then cooled to 40° C. and diluted with 200 ml of dichloromethane in order to reduce its viscosity. The solution was subsequently cooled to room temperature, poured on a mixture of 1.0 kg of crushed ice and 1.5 l of water and extracted. The aqueous phase was extracted with 2.5 l of ethyl acetate, and the combined organic phases were subsequently washed with 2.5 l of water, a solution of 109 g sodium bicarbonate in 2.5 l water, and 250 ml of brine. The organic phase was dried over sodium sulfate, filtered, evaporated at 45° C./1 mbar and dried at 40° C./0.06 mbar for 45 min, to yield 580 g (80%) of a 87:13 exo/endo mixture of product. Purity: 98% (HPLC; ISTD).