反应详情

A solution of 46 mmol of 3,4,5-trifluoro-4′-(4-propylcyclohexyl)biphenyl in 100 ml of dry tetrahydrofuran is cooled to −75° C., and 50 mmol of n-butyllithium (1.6 M solution in n-hexane) are added dropwise under a protective-gas atmosphere at such a rate that the internal temperature does not exceed −75° C. The mixture is subsequently stirred at this temperature for a further 2 hours. 60 mmol of N,N-dimethylformamide are then likewise added dropwise at such a rate that the internal temperature always remains below −75° C. When the addition is complete, the reaction solution is allowed to thaw slowly and is hydrolysed at −10° C. by transfer of the reaction solution into ice-water. The mixture is acidified using hydrochloric acid (pH=3) and extracted with tert-butyl methyl ether. The combined organic extracts are washed with water and saturated sodium chloride solution and dried using sodium sulfate. After the solvent has been removed under reduced pressure, the crude product is chromatographed on silica gel with dichloromethane/n-heptane 1:1 as eluent, giving 3,4,5-trifluoro-4′-(4-propylcyclohexyl)biphenyl-2-carbaldehyde in the form of slightly yellowish crystals; m.p. 62° C.

1. customdoes not exceed −75° C
2. additionWhen the addition
3. extractionextracted with tert-butyl methyl ether
4. washThe combined organic extracts are washed with water and saturated sodium chloride solution
5. customdried
6. customAfter the solvent has been removed under reduced pressure
7. customthe crude product is chromatographed on silica gel with dichloromethane/n-heptane 1:1 as eluent