Reaktion #1736

Reaktionsgleichung

n-BuLi

(Z)-6-bromo-7-hex-1-enyl-1,1,4,4-tetramethyl-1,2,3,4-tetrahydro-naphthalene

CO2

→

(Z)-3-hex-1-enyl-5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-naphthalene-2-carboxylic acid

Lösungsmittel

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.WAITAfter 1/2h.
2. 2
   Sonstigerising to -60° in spite of constant cooling
3. 3
   workup.WAITThe mixture was left
4. 4
   Extraktionextracted with diethyl ether
5. 5
   Waschenwashed with H2O
6. 6
   Trocknendried over Na2SO4
7. 7
   Sonstigethe solvent was removed in a vacuum

Vorschrift

3.72 g of (Z)-6-bromo-7-hex-1-enyl-1,1,4,4-tetramethyl-1,2,3,4-tetrahydro-naphthalene (75% pure) were placed in 25 ml of abs. tetrahydrofuran and treated at -75° with 8.25 ml of 1.55M n-BuLi (hexane) (1.2 eq.). After 1/2h., a CO2 stream was conducted vigorously through the solution for 30 min., with the temperature rising to -60° in spite of constant cooling. The mixture was left to warm to room temperature, poured on to ice/HCl solution, extracted with diethyl ether, washed with H2O, dried over Na2SO4 and the solvent was removed in a vacuum. Two-fold flash chromatography on SiO2 (hexane/ethyl acetate=85/15, then 9/1) yielded 1.06 g of (Z)-3-hex-1-enyl-5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-naphthalene-2-carboxylic acid as colorless crystals.

Quelle