Réaction #1552100

Équation de réaction

methylmagnesium iodide

2,6-dibromo-9H-xanthen-9-one

AcOH

→

2,6-dibromo-9-methylene-9H-xanthene

Rendement 64.7%

Solvants

EtOAc

THF

Conditions de réaction

Traitement

1. 1
   TempératureThe reaction mixture was cooled to 0° C.
2. 2
   Autrequenched with saturated NH4Cl solution (250 mL)
3. 3
   workup.STIRRINGstirred for 30 min
4. 4
   AutreThe volatiles were removed in vacuo
5. 5
   Autrethe organic layer was separated
6. 6
   Extractionthe aqueous phase was extracted with CHCl3 (2×200 mL)
7. 7
   Séchagecombined organics was dried over MgSO4
8. 8
   Filtrationfiltered
9. 9
   Autresolvents removed in vacuo to crude product (9.46 g)
10. 10
    AutreThe crude reaction
11. 11
    workup.STIRRINGthe reaction mixture was stirred at room temperature for 3 hrs
12. 12
    Autrethe volatiles removed in vacuo
13. 13
    Autrethe residue was precipitated from isohexanes

Mode opératoire

Referring to Scheme 10, methylmagnesium iodide (14.12 mL, 3 M in Et2O, 42.4 mmol) was added to a stirred solution of 2,6-dibromo-9H-xanthen-9-one (7-2) (10 g, 28.2 mmol) in THF (30 mL) at 0° C. The reaction mixture was allowed to warm up to rt and stirred for 2 h. The reaction mixture was cooled to 0° C. and quenched with saturated NH4Cl solution (250 mL) and stirred for 30 min. The volatiles were removed in vacuo. The residue was taken up in CHCl3 (200 mL), and the organic layer was separated and the aqueous phase was extracted with CHCl3 (2×200 mL) and combined organics was dried over MgSO4, filtered and solvents removed in vacuo to crude product (9.46 g). The crude reaction was taken up in EtOAc (200 mL) and AcOH was added (20 mL) and the reaction mixture was stirred at room temperature for 3 hrs, the volatiles removed in vacuo and the residue was precipitated from isohexanes to give 2,6-dibromo-9-methylene-9H-xanthene (9-1) (6.43 g, 64.7% yield).

Source