Reaktion #87954

Reaktionsgleichung

N-Bromosuccinimide

methyl 2-(tert-butyldimethylsilyloxy)-6-methylbenzoate

Intermediate 13

methyl 2-(tert-butyldimethylsilyloxy)-6-methylbenzoate

→

methyl 2-bromomethyl-6-(tert-butyldimethylsilyloxy)benzoate

Ausbeute 32.7%

Lösungsmittel

carbon tetrachloride

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturheated to reflux
2. 2
   TemperaturThe mixture was cooled
3. 3
   workup.WAITleft
4. 4
   Filtrationthen filtered through a 25 g silica cartridge
5. 5
   Wascheneluting with a mixture of ethyl acetate and pentane (20%)
6. 6
   SonstigeThe eluent was evaporated to dryness
7. 7
   workup.DISSOLUTIONthe residue was redissolved in carbon tetrachloride (150 mL)
8. 8
   workup.ADDITIONN-bromosuccinimide (6.96 g) was added
9. 9
   TemperaturThe mixture was heated
10. 10
    Temperaturto reflux
11. 11
    workup.ADDITIONazo-bis-isobutyronitrile (0.1 g) was added
12. 12
    SonstigeThe resultant mixture was illuminated with a 500 W tungsten filament lamp overnight
13. 13
    TemperaturAfter cooling
14. 14
    Filtrationthe mixture was filtered
15. 15
    Waschenthe solid was washed with pentane
16. 16
    SonstigeThe combined organic solutions were evaporated to dryness
17. 17
    Sonstigethe residue was purified by chromatography on silica
18. 18
    Wascheneluting with a mixture of TBME and pentane with a gradient of 0-10%

Vorschrift

N-Bromosuccinimide (7.6 g) was added to a solution of methyl 2-(tert-butyldimethylsilyloxy)-6-methylbenzoate (Intermediate 13, 11.9 g) in carbon tetrachloride (150 mL) and the mixture was stirred and heated to reflux. Azo-bis-isobutyronitrile (0.1 g) was added and the mixture was illuminated with a 500 W tungsten filament lamp for 2 hours. The mixture was cooled and left to stand overnight then filtered through a 25 g silica cartridge eluting with a mixture of ethyl acetate and pentane (20%). The eluent was evaporated to dryness and the residue was redissolved in carbon tetrachloride (150 mL) and N-bromosuccinimide (6.96 g) was added. The mixture was heated to reflux and azo-bis-isobutyronitrile (0.1 g) was added. The resultant mixture was illuminated with a 500 W tungsten filament lamp overnight. After cooling, the mixture was filtered and the solid was washed with pentane. The combined organic solutions were evaporated to dryness and the residue was purified by chromatography on silica, eluting with a mixture of TBME and pentane with a gradient of 0-10% to give methyl 2-bromomethyl-6-(tert-butyldimethylsilyloxy)benzoate (4.99 g) as a yellow oil.

Quelle