Réaction #742260

Équation de réaction

(E)-3-[2-(tert-Butyl-dimethyl-silanoxy)-phenyl]-acrylic acid

1-tert-butyl-4-(3-ethoxy-2-methyl-allyl)-benzene

3-(4-tert-butyl-phenyl)-2-methyl-propionaldehyde

→

ester

Rendement 28.2%

(E)-3(2-Hydroxy-phenyl)-acrylic acid 3(4-tert-butyl-phenyl)-1-ethoxy-propyl ester

Rendement 28.2%

Solvants

THF

toluene

Conditions de réaction

Traitement

1. 1
   AutreThe reaction mixture was partitioned between saturated sodium carbonate and hexane
2. 2
   Lavagethe organic layer was washed with brine
3. 3
   Séchagedried over (Na2SO4)
4. 4
   Autreevaporated to dryness
5. 5
   Autreto yield 5.3 g of the crude intermediate (E)-3-[2-(tert-Butyl-dimethyl-silanoxy)-phenyl]-acrylic acid 3-(4-tert-butyl-phenyl)-1-ethoxy-propyl ester as a pale yellow oil
6. 6
   Concentrationthe mixture was concentrated
7. 7
   Autrepurification by repeated flash chromatography

Mode opératoire

A solution of 3.1 g of (E)-3-[2-(tert-Butyl-dimethyl-silanoxy)-phenyl]-acrylic acid, 3.0 g of 1-tert-butyl-4-(3-ethoxy-2-methyl-allyl)-benzene, accessible from 3-(4-tert-butyl-phenyl)-2-methyl-propionaldehyde via a two step procedure according to P. D. Bartlett and A A. Frimer, Heterocycles 11, 419-435, (1978), and 20 mg of p-TSA in 25 ml of toluene was stirred at 0° C. for 4 h and at room temperature for 14 h. The reaction mixture was partitioned between saturated sodium carbonate and hexane and the organic layer was washed with brine, dried over (Na2SO4) and evaporated to dryness to yield 5.3 g of the crude intermediate (E)-3-[2-(tert-Butyl-dimethyl-silanoxy)-phenyl]-acrylic acid 3-(4-tert-butyl-phenyl)-1-ethoxy-propyl ester as a pale yellow oil. This was dissolved in 20 ml of THF and treated at 0° C. with 3.2 g of solid TBAF-3H2O. After 30 min., the mixture was concentrated and purification by repeated flash chromatography yielded 1.2 g of the title ester (a mixture of diastereoisomers) as a pale yellow oil.

Source