Reaktion #43428

Reaktionsgleichung

6,7-dihydro-5H-pyrano[2,3-c]pyridazin-3-yl trifluoromethanesulfonate

potassium carbonate

water

2,4,6-trivinylcyclotriboroxane

→

product

Ausbeute 77.0%

3-Ethenyl-6,7-dihydro-5H-pyrano[2,3-c]pyridazine

Ausbeute 77.0%

Lösungsmittel

1,2-dimethoxyethane

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigepyridine complex (180 mg, 0.75 mmol) (for a preparation of this reagent
2. 2
   workup.STIRRINGAfter stirring for 2 hours at 80° C.
3. 3
   Temperaturthe mixture was cooled
4. 4
   Sonstigepartitioned between dichloromethane and saturated aqueous sodium bicarbonate solution
5. 5
   SonstigeThe layers were separated
6. 6
   Extraktionthe aqueous fraction was extracted twice with 20% methanol/dichloromethane
7. 7
   SonstigeThe combined organic solution was dried
8. 8
   Sonstigeevaporated
9. 9
   Sonstigethe residue chromatographed on silica gel
10. 10
    Wascheneluting with ethyl acetate

Vorschrift

Argon was bubbled for 15 minutes through a solution of 6,7-dihydro-5H-pyrano[2,3-c]pyridazin-3-yl trifluoromethanesulfonate (228 mg, 0.8 mmol) in 1,2-dimethoxyethane (6.5 ml). Tetrakis(triphenylphosphine)palladium(0) (50 mg, 0.0435 mmol) was added and the solution stirred for 20 minutes under argon. The mixture was then treated with potassium carbonate (111 mg, 0.8 mmol), water (1.9 ml) and 2,4,6-trivinylcyclotriboroxane:pyridine complex (180 mg, 0.75 mmol) (for a preparation of this reagent see F. Kerins and D. F. O'Shea, J. Org. Chem. 2002, 67, 4968-4971). After stirring for 2 hours at 80° C., the mixture was cooled and partitioned between dichloromethane and saturated aqueous sodium bicarbonate solution. The layers were separated and the aqueous fraction was extracted twice with 20% methanol/dichloromethane. The combined organic solution was dried, evaporated and the residue chromatographed on silica gel, eluting with ethyl acetate to give product as a white solid (100 mg, 77%).

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