Reaktion #742260

Reaktionsgleichung

(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

Ausbeute 28.2%

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

Ausbeute 28.2%

Lösungsmittel

THF

toluene

Reaktionsbedingungen

Aufarbeitung

1. 1
   SonstigeThe reaction mixture was partitioned between saturated sodium carbonate and hexane
2. 2
   Waschenthe organic layer was washed with brine
3. 3
   Trocknendried over (Na2SO4)
4. 4
   Sonstigeevaporated to dryness
5. 5
   Sonstigeto 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
   Einengenthe mixture was concentrated
7. 7
   Sonstigepurification by repeated flash chromatography

Vorschrift

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.

Quelle