Reaction #1909814

Reaction equation

3-(1-methyl-3-trifluoromethyl-5-chloropyrazol-4-yl)-2-(4-tert-butylthiazol-2-yl)-3-hydroxyacrylonitrile

triethylamine

pivaloyl chloride

→

3-(1-methyl-3-trifluoromethyl-5-chloropyrazol-4-yl)-2-(4-tert-butylthiazol-2-yl)-3-pivaloyloxyacrylonitrile

Yield 26.3%

Solvents

THF

Conditions

Workup

1. 1
   Otherto give a uniform solution
2. 2
   Temperaturewith cooling with ice
3. 3
   Temperaturegradually heated
4. 4
   workup.STIRRINGstirred at room temperature for 8 hours
5. 5
   Extractionextracted with ethyl acetate
6. 6
   Washwashed thrice with saturated saline
7. 7
   DryingAfter having been dried over sodium sulfate
8. 8
   workup.ADDITIONfilled with silica gel
9. 9
   workup.DISTILLATIONThe solvent was distilled off under reduced pressure

Procedure

0.5 g of 3-(1-methyl-3-trifluoromethyl-5-chloropyrazol-4-yl)-2-(4-tert-butylthiazol-2-yl)-3-hydroxyacrylonitrile and 0.14 g of triethylamine were added to 15 ml of THF at room temperature and stirred to give a uniform solution. 0.16 g of pivaloyl chloride was dropwise added to the solution with cooling with ice, then gradually heated, and stirred at room temperature for 8 hours. The reaction mixture was poured into ice water, extracted with ethyl acetate, and washed thrice with saturated saline. After having been dried over sodium sulfate, the resulting product was passed through a short column filled with silica gel. The solvent was distilled off under reduced pressure, and the residual product was applied to silica gel thin-layer chromatography (developer solvent: chloroform) to obtain 0.16 g of 3-(1-methyl-3-trifluoromethyl-5-chloropyrazol-4-yl)-2-(4-tert-butylthiazol-2-yl)-3-pivaloyloxyacrylonitrile (III-6) and 0.35 g of its geometric isomer (III-15).

Source