methyl 2,4-bis-benzyloxy-5-isopropenylbenzoate synthesis
- Product Name:methyl 2,4-bis-benzyloxy-5-isopropenylbenzoate
- CAS Number:912545-08-5
- Molecular formula:C25H24O4
- Molecular Weight:388.46
Yield:912545-08-5 85%
Reaction Conditions:
Stage #1: 5-acetyl-2,4-bis(benzyloxy)benzoic acid methyl ester;Methyltriphenylphosphonium bromidewith potassium tert-butylate in tetrahydrofuran at 15 - 20; for 5.16667 h;Wittig Reaction;
Stage #2: with methanol in tetrahydrofuran;
Steps:
81.4
A solution of potassium terf-butoxide (6.72 Kg, 60.1 mol) in anhydrous THF (60 L) was added over 3 h to a stirred suspension of methyltriphenylphosphonium bromide (21.43 Kg, 60.1 mol) and methyl 5-acetyl-2,4-bis-benzyloxybenzoate (21.3 Kg, 54.6 mol, step 3) in anhydrous tetrahydrofuran (213 L) at 15 0C. The mixture was stirred at 15 0C for 70 mins and the warmed to 20 0C over 60 mins. Methanol (27.3 L) was added to quench excess phosphorus ylide and the solvent was concentrated in vacuo followed by addition of EtOAc and water. The organic phase was treated with activated charcoal, filtered and evaporated to a small volume. The residue was crystallised from boiling MeOH and the solids were collected by suction filtration, washed with methanol and dried under reduced pressure to afford methyl 2,4-bis-benzyloxy-5-isopropenyl-benzoate 18.1 Kg (85%) as pale yellow needles mp 92-94 0C (99.6% pure by hplc).
References:
WO2008/44029,2008,A1 Location in patent:Page/Page column 271
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