Tetrahydrofuran → 1-(3-chloro-2-pyridinyl)-3-(trifluoromethyl)-1H-pyrazole-5-carbonyl Chloride

Participants

Reaction Conditions

Reaction Steps

In a reaction vessel equipped with a thermometer, septum, nitrogen inlet and stirring bar, 500 mg (2.02 mmol) of 1-(3-chloro-2-pyridyl)-3-trifloromethyl-1H-pyrazole were dissolved in 3 ml of dry tetrahydrofuran. By means of a syringe, 2.0 ml of a 2 M solution of isopropyl magnesium chloride in tetrahydrofuran were added dropwise with stirring, while cooling the vessel with an ice bath and keeping the internal temperature at about 20° C. The ice bath was removed and the mixture was stirred for further 20 minutes at 23° C. Then the mixture was cooled again to −5° C. and 4.25 ml of a 20% (w/w) solution of phosgene in toluene were added dropwise with stirring. The mixture was allowed to war at 23° C. and stirred for further 1 h at 23° C. The thus obtained reaction mixture was evaporated to dryness, redissolved in toluene and stirred for further 30 min. at 50° C. Solids were removed by filtration and washed with toluene. The combined filtrates were evaporated to dryness to yield 0.53 g of the title compound with a purity >85% (yield 84.6%).

Provenance & Evidence