Reaction #1499

Reaction equation

1-(4-fluorophenyl)-4-(trans-4-pentyl-4-silacyclohexyl)-1-butyne-3-ol

p-toluenesulfonic acid monohydrate

→

desired product

Yield 15.9%

1-(4-flurophenyl)-4-(trans-4-pentyl-4-silacyclohexyl)-3E-butene-1-yne

Yield 15.9%

Solvents

benzene

Conditions

Workup

1. 1
   Temperaturewas heated
2. 2
   Temperatureunder reflux
3. 3
   Otherto remove the water
4. 4
   OtherThe reaction mixture thus obtained
5. 5
   workup.ADDITIONa mixture of trans- and cis-isomers
6. 6
   workup.ADDITIONwith respect to the silacyclohexane ring, but also a mixture of E- and Z-isomers
7. 7
   OtherHence, the product was separated by chromatography

Procedure

A mixture of 1-(4-fluorophenyl)-4-(trans-4-pentyl-4-silacyclohexyl)-1-butyne-3-ol 8.0 g (24 mmol), p-toluenesulfonic acid monohydrate 1.6 g, and benzene 200 ml was heated under reflux to remove the water and then subjected to a conventional post-treatment. The reaction mixture thus obtained was not only a mixture of trans- and cis-isomers, with respect to the silacyclohexane ring, but also a mixture of E- and Z-isomers, with respect to the double bond. Hence, the product was separated by chromatography to give 1.2 g of the desired product of the trans-E isomer (yield 15.9%).

Source