Trichloroacetyl chloride → HCID 9911260, compound

Participants

Reaction Steps

3-Cyano-1-(2,2-dichloro-4-trifluoromethylphenyl)-4-vinylpyrazole (5.00 g, 15.06 mmol, WO97/07102-A1) was dissolved in anhydrous diethyl ether (50 ml) in a dry, nitrogen-flushed flask. Activated zinc (2.97 g, 45.8 mmol) was added and the suspension was vigorously stirred. A mixture of trichloroacetyl chloride (3.57 ml, 37.65 mmol) and phosphorus oxychloride (4.1 ml, 37.65 mmol) in diethyl ether (20 ml) was added dropwise at room temperature via a pressure-equalising dropping funnel over a period of 30 minutes--the resulting exotherm being controlled by the rate of addition. On completion of addition, the mixture was heated to reflux for 4 hr then cooled to room temperature. The mixture was filtered and poured onto 200 ml of crushed ice before extracting with diethyl ether (3×100 ml). The combined organics were washed successively with saturated aqueous NaHCO3 solution and brine before drying over MgSO4, filtering, and evaporating the ether in vacuo to leave a black oil. This was purified by silica chromatography (eluting with 10% diethyl ether/hexane) to give 3.80 g of the title compound as a white solid.

Provenance & Evidence