Hydrochloric Acid → HCID 19365499, compound

Participants

Reaction Steps

To a mixed solution of 35.5 g of sodium carbonate and 120 ml of water was added dropwise 22.7 g of 1,1-dibromo-3,3,3-trifluoroacetone at such a rate that the temperature of the reaction mixture became not higher than 55° C. After completion of the dropwise addition, the mixture was stirred at room temperature for 30 minutes, followed by adding 150 ml of water and then 12.8 g of 2-amino-2-(4-chloro-2-fluorophenyl)acetamide, and the reaction was allowed to proceed at 60° C. for 2 hours. After completion of the reaction, the reaction mixture was cooled to 10° C. or lower, made acidic by adding 20 ml of concentrated hydrochloric acid at the same temperature, and extracted with ethyl acetate. The organic layer was washed with water and then saturated sodium chloride solution, dried with anhydrous magnesium sulfate, and concentrated. The residue was subjected to silica gel column chromatography (eluent, hexane/ethyl acetate=4:1), which afforded 5.83 g (yield, 32%) of the desired compound, 3-(4-chloro-2-fluorophenyl)-6-trifluoromethyl-2-oxo-1,2-dihydropyrazine (compound 1-1005; m.p., 83.2° C.). The continued elution with the above solvent system gave 4.32 g of the configurational isomer, 3-(4-chloro-2-fluorophenyl)-5-trifluoromethyl-2-oxo-1,2-dihydropyrazine.

Provenance & Evidence