Reaction #1960494

Reaction equation

hydrochloric acid

7,8-difluoro-2-pentyl-6-[1-(4-propylcyclohexyl)prop-2-ynyloxy]chroman

potassium fluoride

water

→

5,6-difluoro-3-pentyl-8-(4-propylcyclohexyl)-1,2,3,8-tetrahydropyrano[3,2-f]chromene

Solvents

N,N-diethylaniline

Conditions

Workup

1. 1
   TemperatureAfter cooling
2. 2
   ExtractionThe batch is extracted with MTBE
3. 3
   Washthe organic phase is washed with saturated sodium chloride solution
4. 4
   OtherThe solution is dried
5. 5
   Otherevaporated to dryness
6. 6
   OtherThe crude product is purified by column chromatography (SiO2, 1-chlorobutane:pentane=4:1)

Procedure

9.7 g (23.2 mmol) of 7,8-difluoro-2-pentyl-6-[1-(4-propylcyclohexyl)prop-2-ynyloxy]chroman are heated at 200° C. for 6 h together with 2.7 g (46.5 mmol) of potassium fluoride in 75 ml of N,N-diethylaniline. After cooling, water is added, and the mixture is acidified using 25% hydrochloric acid. The batch is extracted with MTBE, and the organic phase is washed with saturated sodium chloride solution. The solution is dried using sodium sulfate and evaporated to dryness. The crude product is purified by column chromatography (SiO2, 1-chlorobutane:pentane=4:1), giving 5,6-difluoro-3-pentyl-8-(4-propylcyclohexyl)-1,2,3,8-tetrahydropyrano[3,2-f]chromene as a pale-brown oil.

Source