反応 #87954

反応方程式

N-Bromosuccinimide

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

Intermediate 13

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

→

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

収率 32.7%

溶媒

carbon tetrachloride

反応条件

後処理

1. 1
   温度heated to reflux
2. 2
   温度The mixture was cooled
3. 3
   workup.WAITleft
4. 4
   ろ過then filtered through a 25 g silica cartridge
5. 5
   洗浄eluting with a mixture of ethyl acetate and pentane (20%)
6. 6
   その他The 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
   温度The mixture was heated
10. 10
    温度to reflux
11. 11
    workup.ADDITIONazo-bis-isobutyronitrile (0.1 g) was added
12. 12
    その他The resultant mixture was illuminated with a 500 W tungsten filament lamp overnight
13. 13
    温度After cooling
14. 14
    ろ過the mixture was filtered
15. 15
    洗浄the solid was washed with pentane
16. 16
    その他The combined organic solutions were evaporated to dryness
17. 17
    その他the residue was purified by chromatography on silica
18. 18
    洗浄eluting with a mixture of TBME and pentane with a gradient of 0-10%

実験手順

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.

出典