Reaction #4819

Reaction equation

1,2,4-triazole

potassium carbonate

1,3-dichloroacetone

ammonium chloride

phenylmagnesium bromide

heptafluoropropyl iodide

→

2-heptafluoropropyl-2-(1H-1,2,4-triazol-1-ylmethyl)oxirane

Yield 2.1%

Solvents

dimethylformamide

diethylether

water

diethylether

brine

diethylether

diethylether

Conditions

Workup

1. 1
   Temperaturecooled to -70°
2. 2
   workup.ADDITIONmole) was then added dropwise at such a rate that the temperature of the reaction mixture
3. 3
   Otherdid not exceed -65°
4. 4
   workup.ADDITIONWhen the addition
5. 5
   Otherdid not exceed -65°
6. 6
   workup.ADDITIONWhen the addition
7. 7
   workup.STIRRINGstirring
8. 8
   workup.WAITwas continued at -70° for 1 hour
9. 9
   Otherthe aqueous layer was separated
10. 10
    Extractionextracted with diethylether (2×25 ml)
11. 11
    DryingThe combined diethylether extracts were dried (MgSO4)
12. 12
    Otherevaporated
13. 13
    Otherto give a pale yellow liquid which
14. 14
    workup.STIRRINGStirring
15. 15
    workup.WAITwas continued for 2.5 hours at room temperature
16. 16
    OtherThe aqueous layer was separated
17. 17
    Extractionextracted with diethylether (2×50 ml)
18. 18
    Dryingthe combined diethylether extracts were dried (MgSO4)
19. 19
    Otherevaporated
20. 20
    Otherflash chromatographed on silica (230-400 mesh)
21. 21
    Washeluting with ethyl acetate

Procedure

A solution of heptafluoropropyl iodide (14.58 g, 49.2 m.mole) in diethylether (65 ml) was stirred and cooled to -70°. A solution of phenylmagnesium bromide in diethylether (15.75 ml of a 3 molar solution; 47.25 m.mole) was then added dropwise at such a rate that the temperature of the reaction mixture did not exceed -65°. When the addition was complete, stirring was continued for 15 minutes and a solution of 1,3-dichloroacetone (5 g, 39.4 m.mole) in diethylether was then added dropwise, again at such a rate that the temperature of the reaction mixture did not exceed -65°. When the addition was complete, stirring was continued at -70° for 1 hour and then a saturated aqueous solution of ammonium chloride (50 ml) was added. The reaction mixture was allowed to warm to room temperature, water (25 ml) was added, and the aqueous layer was separated and extracted with diethylether (2×25 ml). The combined diethylether extracts were dried (MgSO4) and evaporated to give a pale yellow liquid which was immediately added to a stirred mixture of 1,2,4-triazole (2.7 g, 39.4 m.mole), anhydrous potassium carbonate (10.8 g, 78.75 m.mole) and dimethylformamide (DMF) (125 ml). Stirring was continued for 2.5 hours at room temperature and the reaction mixture was then poured into a mixture of diethylether (250 ml) and brine (800 ml). The aqueous layer was separated and extracted with diethylether (2×50 ml) and the combined diethylether extracts were dried (MgSO4) and evaporated. The residue was then flash chromatographed on silica (230-400 mesh), eluting with ethyl acetate to give, as a pale brown solid, 2-heptafluoropropyl-2-(1H-1,2,4-triazol-1-ylmethyl)oxirane (240 mg), which was used immediately in the next step.

Source