Reaction #742260

Reaction equation

(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

Yield 28.2%

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

Yield 28.2%

Solvents

THF

toluene

Conditions

Workup

1. 1
   OtherThe reaction mixture was partitioned between saturated sodium carbonate and hexane
2. 2
   Washthe organic layer was washed with brine
3. 3
   Dryingdried over (Na2SO4)
4. 4
   Otherevaporated to dryness
5. 5
   Otherto 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
   Otherpurification by repeated flash chromatography

Procedure

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