Reaktion #52302

Reaktionsgleichung

piperonal

triphenylphosphine

carbontetrabromide

→

title compound

Ausbeute 74.0%

5-(2,2-Dibromo-vinyl)-benzo[1,3]dioxole

Ausbeute 74.0%

Lösungsmittel

DCM

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONAfter the addition
2. 2
   Sonstigethe ice-water bath was removed
3. 3
   Sonstigequenched with saturated NaHCO3
4. 4
   SonstigeAqueous was separated
5. 5
   Extraktionextracted with dichloromethane (2 times)
6. 6
   Trocknendried over Na2SO4
7. 7
   Filtrationfiltered
8. 8
   Einengenconcentrated
9. 9
   Sonstigeto give a redish colored residue, that
10. 10
    Filtrationwas filtered through a short path silica gel plug
11. 11
    Wascheneluting with DCM/hexane (10% to 20%)

Vorschrift

To a solution of piperonal (4.5 g, 30 mmol) and triphenylphosphine (24 g, 90 mmol) in DCM (120 mL) in an ice-water bath was added a solution of carbontetrabromide (15 g, 45 mmol) over a 10 minutes period. After the addition completed, the ice-water bath was removed, the reaction stirred at ambient temperature for 2 h, and then quenched with saturated NaHCO3. Aqueous was separated, and extracted with dichloromethane (2 times). The organic layers were combined, dried over Na2SO4, filtered, and concentrated to give a redish colored residue, that was filtered through a short path silica gel plug, eluting with DCM/hexane (10% to 20%). Concentration of the filtrate gave the title compound (6.5 g, 74% yield) as a pale yellow liquid. 1H NMR (CDCl3) δ 7.36 (s, 1H), 7.18 (d, 1H, J=1.6 Hz), 6.95 (dd, 1H, J=1.5, 8.1 Hz), 6.79 (d, 1H, J=8.1 Hz), 5.99 (s, 2H).

Quelle