3-(Trifluoromethyl)pyridine-2-carbonitrile → 1-[3-(Trifluoromethyl)pyridin-2-yl]ethan-1-one

Participants

Reaction Conditions

Reaction Steps

2-cyano-3-trifluoromethylpyridine (179 g; 1.04 mol) and THF (1200 mL) are combined in a 5.0 liter flask and cooled with and ice and salt mixture. 3.0 M MeMgI/Et2O (694 mL) is added drop wise over a period of 90 minutes while maintaining the inside temperature of the reaction mixture below 5° C. After the addition, the reaction mixture is stirred at 0° C. for another 30 minutes, and is then slowly poured over 3.0 kg of crushed ice in a 12 liter vessel with stirring (6° C.). The undissolved magnesium salts from the original reaction vessel are quenched with ice (750 g) and transferred to the 12 liter vessel. The resulting mixture is acidified with 6.0 N aq. HCl to pH 2.0 and stirred for 30 minutes at <10° C. The mixture is then extracted with EtOAc (5×1 liters), and the combined extracts are washed with brine (1.5 liters) and dried with Na2SO4 (500 g). The dried extract is filtered and concentrated in vacuum at 40° C. to afford a dark brown oil. The crude product is distilled under vacuum to give 2-acetyl-3-trifluoromethylpyridine as a clear pale yellow liquid.

Provenance & Evidence