Reaktion #1743

Reaktionsgleichung

ethanol

hydrogen peroxide

4-(4-dimethylaminomethylphenyl)-cyclohexanone

lithium tri-sec.-butyl-borohydride

→

cis-4-(4-Dimethylaminomethylphenyl)-cyclohexanol

Lösungsmittel

tetrahydrofuran

tetrahydrofuran

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.WAITThe reaction mixture is then left
2. 2
   Sonstigeto react for 3 hours at -70° C.
3. 3
   SonstigeThe organic phase is separated off
4. 4
   Extraktionextracted with 50 ml of ethyl acetate
5. 5
   TrocknenThe combined organic extracts are dried with sodium sulphate
6. 6
   Sonstigeevaporated down in vacuo
7. 7
   workup.ADDITIONwhich consists of a mixture of cis/trans-4-(4-dimethylaminomethylphenyl)cyclohexanol (trans fraction <5%)
8. 8
   Sonstigeis purified by column chromatography (aluminium oxide neutral, activity stage III, ICN; petroleum ether/methylethyl ketone=5:1)

Vorschrift

50 ml (0.05 mol) of a 1 molar solution of lithium tri-sec.-butyl-borohydride in absolute tetrahydrofuran are diluted with 100 ml of absolute tetrahydrofuran under a nitrogen atmosphere and then, at -65° C. to -70° C., with stirring and within 10 minutes, a solution of 5.8 g (0.025 mol) of 4-(4-dimethylaminomethylphenyl)-cyclohexanone in 50 ml of absolute tetrahydrofuran is added thereto. The reaction mixture is then left to react for 3 hours at -70° C. and then heated to ambient temperature within 1 hour. It is then hydrolysed with 20 ml of 75% aqueous ethanol and the organoborane is oxidised with alkaline hydrogen peroxide (10 ml of 6M NaOH/15 ml 30% H2O2). The organic phase is separated off, the aqueous phase is saturated with potassium carbonate and extracted with 50 ml of ethyl acetate. The combined organic extracts are dried with sodium sulphate and evaporated down in vacuo. The greasy residue remaining, which consists of a mixture of cis/trans-4-(4-dimethylaminomethylphenyl)cyclohexanol (trans fraction <5%) is purified by column chromatography (aluminium oxide neutral, activity stage III, ICN; petroleum ether/methylethyl ketone=5:1).

Quelle