Reaktion #75632

Reaktionsgleichung

2-fluoro-4-iodo-3-pyridinecarbaldehyde

1-ethoxyvinyltributyltin

potassium fluoride

→

expected product

4-(1-Ethoxyvinyl)-2-fluoro-3-pyridinecarbaldehyde

Lösungsmittel

dioxane

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturThe reaction mixture is heated
2. 2
   Temperaturat reflux until the starting material
3. 3
   SonstigeAfter returning to room temperature
4. 4
   workup.ADDITIONis added to the reaction mixture
5. 5
   Temperaturis maintained for 10 minutes in order
6. 6
   Sonstigeprecipitation of the tributyltin fluoride, which
7. 7
   Filtrationis filtered off
8. 8
   ExtraktionThe aqueous phase is extracted 3 times with dichloromethane
9. 9
   Trocknendried over magnesium sulphate
10. 10
    Einengenconcentrated
11. 11
    Sonstigepurified by chromatography over a silica column

Vorschrift

There are mixed in succession 8 g (31.9 mmol) of 2-fluoro-4-iodo-3-pyridinecarbaldehyde (described in J.O.C, 1993, 58, pp. 7832), 12.7 g (35.96 mmol) of 1-ethoxyvinyltributyltin and 740 mg of tetrakis(triphenylphosphine)palladium (2% molar) in 280 ml of dioxane. The reaction mixture is heated at reflux until the starting material has disappeared completely. After returning to room temperature a solution of potassium fluoride is added to the reaction mixture. Vigorous stirring is maintained for 10 minutes in order to cause precipitation of the tributyltin fluoride, which is filtered off. The filtrate is plunged into a sodium chloride solution. The aqueous phase is extracted 3 times with dichloromethane and then the organic phases are combined, dried over magnesium sulphate, concentrated and purified by chromatography over a silica column, using a dichloromethane/cyclohexane mixture (95/5) as eluant to yield the expected product.

Quelle