Reaction #1343

Reaction equation

triethyl orthoacetate

5,5-dichloro-4-hydroxy-2-methyl-6,6,6-trifluorohex-2-ene

isobutyric acid

→

ethyl 6,6-dichloro-3,3-dimethyl-7,7,7-trifluorohept-4-enoate

Conditions

Workup

1. 1
   Temperaturewas heated at the reflux temperature
2. 2
   Othercondensed
3. 3
   Othercollected in a Dean & Stark apparatus
4. 4
   workup.ADDITIONcontaining molecular sieves (4A)
5. 5
   Otherto collect the by-product ethanol
6. 6
   Otherseparate it from the orthoacetate which
7. 7
   OtherAfter 30 minutes the more volatile components were removed by evaporation under reduced pressure
8. 8
   Othercollected
9. 9
   TemperatureThis was then heated with isobutyric acid (10 μl) at the reflux temperature for 16 hours under a condenser
10. 10
    workup.ADDITIONcontaining molecular sieves (4A)
11. 11
    Otherto remove ethanol from the condensate
12. 12
    OtherThe residual oil was subjected to purification by column chromatography
13. 13
    workup.ADDITIONa 15:1 (by volume) mixture of hexane

Procedure

A mixture of triethyl orthoacetate (25 ml), 5,5-dichloro-4-hydroxy-2-methyl-6,6,6-trifluorohex-2-ene (3.5 g), and isobutyric acid (0.11 g) was heated at the reflux temperature. The refluxing volatiles were condensed and collected in a Dean & Stark apparatus containing molecular sieves (4A) to collect the by-product ethanol and separate it from the orthoacetate which was returned to the mixture. After 30 minutes the more volatile components were removed by evaporation under reduced pressure and the residual oil (consisting principally of 5,5-dichloro-4-(1,1-diethoxyethoxy)-2-methyl-6,6,6-trifluorohex-2-ene, 3.8 g) collected. This was then heated with isobutyric acid (10 μl) at the reflux temperature for 16 hours under a condenser containing molecular sieves (4A) to remove ethanol from the condensate. The residual oil was subjected to purification by column chromatography using a 15:1 (by volume) mixture of hexane:ethyl acetate as eluant and a silica gel column (230-400 mesh, 60 Å) to obtain ethyl 6,6-dichloro-3,3-dimethyl-7,7,7-trifluorohept-4-enoate, identified by nuclear magnetic resonance, and gas chromatographic mass-spectroscopy.

Source