Reaction #2006465

Reaction equation

702

4-Carbethoxy-1,6-heptadiene

2,6-dibromophenol

→

703

Yield 71.1%

(±)-3-Cyclopentenecarboxylic Acid, Ethyl Ester

Yield 71.1%

Solvents

toluene

toluene

Conditions

Workup

1. 1
   TemperatureThe resulting suspension was heated
2. 2
   Temperatureat reflux under nitrogen for 1 h
3. 3
   Otherthe solvent was evaporated in vacuo
4. 4
   Otherdried in vacuo for 30 min
5. 5
   TemperatureAfter being cooled to r.t.
6. 6
   Filtrationthe mixture was filtered through a celite
7. 7
   Washthe celite was rinsed with t-BuOMe
8. 8
   WashThe combined filtrates were washed with 1% NaOH soln
9. 9
   Concentrationwater, and brine, and concentrated by evaporation at reduced pressure
10. 10
    workup.DISTILLATIONThe residue was distilled (37-38° C./1 Torr)

Procedure

A flame-dried 500 mL flask was charged with 2,6-dibromophenol (1.20 g, 4.76 mmol), tungsten oxychloride (0.813 g, 2.38 mmol), and anhydrous toluene (25 mL). The resulting suspension was heated at reflux under nitrogen for 1 h, and then the solvent was evaporated in vacuo. The solid residue was broken up with a spatula and dried in vacuo for 30 min. To the residue were added toluene (160 mL), Et4Pb (1.54 g, 4.76 mL), and 702 (22 g, 131.0 mmol). The mixture was heated at 90° C. under nitrogen for 1.5 h. After being cooled to r.t., the mixture was filtered through a celite, and the celite was rinsed with t-BuOMe. The combined filtrates were washed with 1% NaOH soln, water, and brine, and concentrated by evaporation at reduced pressure. The residue was distilled (37-38° C./1 Torr) to give 13.06 g (71%) of 703 as a colorless liquid. 1H NMR (400 MHz, CDCl3) δ 5.67 (s, 2H, CH═CH), 4.14 (q, 2H, J=7.2 Hz, OCH2), 3.11 (pentuplet, J=7.6 Hz, 1H, CH), 2.65 (d, J=7.6 Hz, 4H, 2CH2), 1.27 (t, J=7.2 Hz, 3H, CH3).

Source