Reaction #1960498

Reaction equation

hydrochloric acid

trimethyl borate

hydrogen peroxide

7,8-difluoro-2-(4-propylcyclohexyl)-1,2,3,4-tetrahydronaphthalene

n-BuLi

→

3,4-difluoro-6-(4-propylcyclohexyl)-5,6,7,8-tetrahydronaphthalen-2-ol

Solvents

Water

acetic acid

THF

Conditions

Workup

1. 1
   TemperatureThe mixture is warmed to 30° C.
2. 2
   workup.ADDITIONWhen the addition
3. 3
   ExtractionThe solution is extracted a number of times with MTBE
4. 4
   Washthe combined organic phases are washed successively with water, sat. sodium chloride soln
5. 5
   OtherThe solution is dried
6. 6
   Otherevaporated to dryness
7. 7
   OtherThe crude product is purified by column chromatography (SiO2, toluene)
8. 8
   OtherThe further purification
9. 9
   Otheris carried out by crystallisation from n-heptane

Procedure

77.0 g (about 0.26 mol) of crude 7,8-difluoro-2-(4-propylcyclohexyl)-1,2,3,4-tetrahydronaphthalene are initially introduced in 500 ml of THF, and 200.0 ml (0.32 mol) of n-BuLi (15% soln. in hexane) are added at −70° C. After 3 h at this temperature, 37.0 ml (0.33 mol) of trimethyl borate are added dropwise, the batch is warmed to 0° C., and 80 ml of dilute acetic acid (about 30%) are added. The mixture is warmed to 30° C., and 70 ml of hydrogen peroxide solution (35%) are carefully added. When the addition is complete, the mixture is stirred at RT for 2 h. Water is added, and the batch is acidified using dil. hydrochloric acid. The solution is extracted a number of times with MTBE, and the combined organic phases are washed successively with water, sat. sodium chloride soln. and ammonium iron(II) sulfate soln. The solution is dried using sodium sulfate and evaporated to dryness. The crude product is purified by column chromatography (SiO2, toluene). The further purification is carried out by crystallisation from n-heptane, giving 3,4-difluoro-6-(4-propylcyclohexyl)-5,6,7,8-tetrahydronaphthalen-2-ol as a colourless solid.

Source