Reaction #888

Reaction equation

1-(4-tolyloxy)-1,2-bis-(4-bromobenzoyl)ethylene

KBr

→

2,5-bis(4-Bromophenyl)-3-(p-tolyloxy)furan

Solvents

phosphorus trichloride

Conditions

Workup

1. 1
   Temperatureunder reflux for 3-4 hr (TLC followed)
2. 2
   OtherThe excess PCl3 was removed by distillation
3. 3
   Otherthe residue was triturated with ice/water (exothermic reaction)
4. 4
   ExtractionThe solution was extracted with dichloromethane (75 ml)
5. 5
   Washthe dichloromethane layer was washed with saturated sodium bicarbonate solution, water
6. 6
   Otherdried (Na2 SO4)
7. 7
   OtherThe solvent was removed under reduced pressure
8. 8
   OtherThe residual solid was chromatographed over silica gel
9. 9
   OtherAn off white crystalline solid was obtained

Procedure

A solution of 5.0 g (0.01 mole) 1-(4-tolyloxy)-1,2-bis-(4-bromobenzoyl)ethylene in 10 ml phosphorus trichloride was heated under reflux for 3-4 hr (TLC followed). The excess PCl3 was removed by distillation and the residue was triturated with ice/water (exothermic reaction). The solution was extracted with dichloromethane (75 ml) and the dichloromethane layer was washed with saturated sodium bicarbonate solution, water, and dried (Na2 SO4). The solvent was removed under reduced pressure. The residual solid was chromatographed over silica gel using ether:hexane (2:8 to 1:1) as eluant. An off white crystalline solid was obtained, 2.78 g (56%), mp 92°-3° C. IR (KBr) 2923, 2851, 1560, 1506, 1467, 1390, 1209, 1072, 1066, 945, 825, 707, 486. 1H NMR (CDCl3 /35° C.) 7.69 (d, 2H, J=8.8), 7.46-7.43 (m, 6H), 7.12 (d, 2H, J=8.3), 7.0 (d, 2H, J=8.3), 6.47 (s, 1H), 2.31 (s, 3H). 13C NMR (CDCl3 /135° C.) 150.8, 150.1, 142.8, 139.3, 133.0, 131.9, 131.7, 130.3, 129.1, 128.6, 125.1, 125.0, 121.8, 120.5, 117.1, 102.7, 20.6. MS m/e 484 (M+).

Source