Hexafluorophosphoric acid → 2-Bromo-5-(4-chloro-phenyl)-3-fluoro-pyridine

Participants

Reaction Conditions

Reaction Steps

243 mg (3.53 mmol) sodium nitrite in 0.5 mL water are added dropwise at −5° C. to a solution of 1.00 g (3.53 mmol) 2-bromo-5-(4-chloro-phenyl)-pyridin-3-ylamine in 2 mL water and 2.04 mL concentrated HCl. Then at 0° C. 1.56 mL (10.6 mmol) 60% hexafluorophosphoric acid in water are added and the reaction is stirred for a further hour at 0° C. The diazonium salt is suction filtered, washed with cold water, isopropanol and ether and dried overnight in the desiccator at RT and 7 mbar. This is then added batchwise at 90° C. to 50 mL PE (boiling point 100-140° C.). After the reaction solution has cooled the mixture is made alkaline with saturated Na2CO3 solution. The aqueous phase is extracted with EtOAc and the organic phase is washed successively with saturated Na2CO3 solution and water. The organic phase is dried over MgSO4 and the solvent is eliminated i.vac. The purification is carried out by column chromatography on silica gel (PE).

Provenance & Evidence