Acetic Anhydride → Ethyl beta-cyclopropyl-alpha-ethoxymethylene-beta-ketopropionate
Reaktionsgleichung
[CH:1]1([CH2:4][C:5](=O)[C:6]([O:8][CH2:9][CH3:10])=[O:7])[CH2:3][CH2:2]1.[CH:12](OCC)(OCC)[O:13][CH2:14][CH3:15].C(OC(=O)C)(=[O:24])C>>[CH:1]1([C:4](=[O:24])[C:5](=[CH:12][O:13][CH2:14][CH3:15])[C:6]([O:8][CH2:9][CH3:10])=[O:7])[CH2:2][CH2:3]1Komponenten
4
Versuchsvorschrift
Ethyl β-cyclopropyl-α-ketopropionate (247.0 g, 1.58 mole) [prepared according to the procedure described in J. Am. Chem. Soc., 70 , 497 (1948)], triethyl orthoformate (468.3 g, 3.16 mole) and acetic anhydride (484.0 g, 4.74 mole) were combined and the solution was stirred at reflux for 4 h and at ambient temperature for 17 h. The excess reagents were distilled at water aspirator pressure (maximum head temperature permitted was 72° C.) and the oily pot residue was stirred at 10° C. with a mixture of ether and water. The ether layer was separated, washed once with cold water and dried over Na2SO4. Removal of the solvent gave 321.5 g (96%) of an orange-red liquid that was used directly in the next step.