Réaction #1552102

Équation de réaction

Phosphorus pentoxide

(2,6-dibromo-9H-xanthen-9-yl)methanol

→

2,7-dibromodibenzo[b,f]oxepine

Rendement 79.4%

Solvants

toluene

Conditions de réaction

Traitement

1. 1
   Températurethe suspension was heated
2. 2
   Températureunder reflux for 20 min
3. 3
   Autretoluene was removed by decantation
4. 4
   LavageThe residual solid was washed with toluene (2×100 mL) by further decantation
5. 5
   TempératureThe combined organics were cooled in an ice bath
6. 6
   workup.ADDITIONbrine (400 mL) was added slowly
7. 7
   AutreThe layers were separated
8. 8
   Lavagethe organic washed with water (300 mL), brine (300 mL)
9. 9
   Séchagedried over anhydrous MgSO4
10. 10
    Autreevaporated to dryness
11. 11
    Autreto give a yellow oily solid
12. 12
    AutreThe product was purified by column chromatography (SiO2

Mode opératoire

Phosphorus pentoxide (5.04 g, 35.5 mmol) was added portion-wisely to a stirred solution of (2,6-dibromo-9H-xanthen-9-yl)methanol (10-1) (1.01 g, 2.73 mmol) in toluene (100 mL) and the suspension was heated under reflux for 20 min. The mixture was allowed to cool to rt and toluene was removed by decantation. The residual solid was washed with toluene (2×100 mL) by further decantation. The combined organics were cooled in an ice bath and brine (400 mL) was added slowly. The layers were separated and the organic washed with water (300 mL), brine (300 mL), dried over anhydrous MgSO4 and evaporated to dryness, to give a yellow oily solid. The product was purified by column chromatography (SiO2, O-10% EtOAc/isohexanes) to give 2,7-dibromodibenzo[b,f]oxepine (10-2) (763 mg, 79% yield) as a clear oil. 1H NMR (CDCl3): δ 7.41-7.36 (1H, m), 7.33-7.31 (1H, m), 7.29-7.24 (2H, m), 7.04-6.99 (2H, m), 6.68-6.57 (2H, m) ppm.

Source