Reaktion #1734

Reaktionsgleichung

CO2

nBuLi

2-bromo-3-hexyl-5,5-dimethyl-6,7,8,9-tetrahydro-5H-benzocycloheptene

→

3-hexyl-5,5-dimethyl-6,7,8,9-tetrahydro-5H-benzocycloheptene-2-carboxylic acid

Lösungsmittel

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigethe cooling bath was removed
2. 2
   workup.WAITAfter 10 min.
3. 3
   workup.ADDITIONthe mixture was poured on to ice/NH4Cl solution
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

This 3.21 g of 2-bromo-3-hexyl-5,5-dimethyl-6,7,8,9-tetrahydro-5H-benzocycloheptene were placed in 30 ml of abs. tetrahydrofuran under Ar and treated at -78° with 6.75 ml of 1.55M nBuLi (hexane) (1.1 eq.). The metal/halogen exchange was followed by gas chromatography (GC). After 40 min., a large excess of CO2 gas was introduced and the cooling bath was removed. After 10 min., the mixture was poured on to ice/NH4Cl solution, extracted with diethyl ether, washed with H2O, dried over Na2SO4 and the solvent was removed in a vacuum. Flash chromatography on SiO2 (hexane/ethyl acetate=8/2) yielded 2.26 g of 3-hexyl-5,5-dimethyl-6,7,8,9-tetrahydro-5H-benzocycloheptene-2-carboxylic acid as white crystals of m.p. 74°-75°.

Quelle