Cesium fluoride → 5-Chloro-2,3-difluoropyridine

Participants

Reaction Conditions

Reaction Steps

A suspension of 64.6 g (1.1 mol) of potassium fluoride and 11.25 g (0.075 mol) of cesium-fluoride in 240 ml of sulfolane (1,1-dioxo-tetrahydrothiophene) is heated to 140° C. By reducing the pressure 50 ml of sulfolane are distilled off. To the suspension a solution of 61.4 g (0.37 mol) of 2,5-dichloro-3-fluoropyridine in 20 ml of sulfolane is added. The reaction-mixture is then stirred for 35 hours at a temperature of 140°, cooled and poured into ice/water. The organic material is extracted with ether. The ethereal layer is washed with water dried over magnesium sulfate, filtered and evaporated to yield 48.7 g of a colourless oil (88% of the theory) which boils at 65°-66° at 133 mbar.

Provenance & Evidence