Reaction #69658

Reaction equation

tetrahydrofuran

n-butyl lithium

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

tetrahydrofuran

Methanol

→

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

Yield 36.0%

Conditions

Workup

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

Procedure

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.

Source