Cesium fluoride → 2,2,2-Trifluoro-1-(pyrazin-2-yl)ethan-1-one

Participants

Reaction Steps

Pyrazine carboxylate methyl ester (7 g) was dissolved in dimethoxy ethane (monoglyme) (20 mL) and treated at room temperature with trimethylsilyltrifluoro-methane (10 mL; 1.44 eq) and caesium fluoride (0.77 g; 0.1 eq) that had been freshly dried at for 10 minutes under vacuum while being heated with a heat gun. After 18 hours at room temperature the reaction mixture was concentrated under reduced pressure at room temperature, and the residue was dissolved in tetrahydrofuran (50 mL) and acetic acid (20 mL) and treated with tert-butylammonium fluoride (50 mL; 1M THF solution) for 3 hours at room temperature. The reaction was diluted with ethyl acetate, and washed with dilute aqueous sodium bicarbonate solution (3 times), brine, dried over anhydrous sodium sulfate, and evaporated to dryness under reduced pressure to an oil. Trituration of the oil with dichloromethane/hexane gave 2,2,2-trifluoro-1-(pyrazin-2-yl)ethanone (18) as a brown solid (2.9 g).

Provenance & Evidence