Reaktion #69658

Reaktionsgleichung

tetrahydrofuran

n-butyl lithium

methyl 5-acetyl-2,4-bis-benzyloxybenzoate

tetrahydrofuran

Methanol

→

methyl 2,4-bis-benzyloxy-5-isopropenyl-benzoate

Ausbeute 36.0%

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturto warm to room temperature
2. 2
   workup.STIRRINGwas stirred for 16 hours
3. 3
   Sonstigethe solvent was removed in vacuo
4. 4
   SonstigeThe residues were partitioned between dichloromethane and water
5. 5
   Sonstigethe organic layer was separated
6. 6
   Sonstigethe solvent removed in vacuo
7. 7
   Sonstigeto afford a brown gum that
8. 8
   Sonstigewas purified by column chromatography on silica
9. 9
   WaschenElution with 7% ethyl acetate in petroleum ether

Vorschrift

A stirred suspension of methyltriphenylphosphonium bromide (1.96 g, 5.5 mmol) in anhydrous tetrahydrofuran (20 ml) at 0° C. under a nitrogen atmosphere was treated dropwise with n-butyl lithium (1.6 M in hexanes, 3.5 ml, 5.5 mmol) and the resulting bright yellow solution was stirred at 0° C. for 30 minutes. A solution of methyl 5-acetyl-2,4-bis-benzyloxybenzoate (1.95 g, 5.00 mmol) in anhydrous tetrahydrofuran (20 ml) was added dropwise and the resulting mixture was allowed to warm to room temperature and was stirred for 16 hours. Methanol (10 ml) was added and the solvent was removed in vacuo. The residues were partitioned between dichloromethane and water, the organic layer was separated and the solvent removed in vacuo to afford a brown gum that was purified by column chromatography on silica. Elution with 7% ethyl acetate in petroleum ether afforded methyl 2,4-bis-benzyloxy-5-isopropenyl-benzoate as a colourless solid (700 mg, 36%). 1H NMR (DMSO-d6) 7.59 (1H, s), 7.52 (2H, d), 7.64-7.32 (8H, m), 6.97 (1H, s), 5.28 (2H, s), 5.22 (2H, s), 5.09 (1H, s), 5.04 (1H, s), 3.76 (3H, s), 2.02 (3H, s). MS: [M+H]+ 389.

Quelle