Iodine → 2,4-Dichloro-3-iodopyridine

Participants

Reaction Conditions

Reaction Steps

To a solution of 2,4-dichloropyridine (5.2 g, 35.137 mmol) and DIPEA (3.911 g, 38.651 mmol) in dry THF (40 ml) cooled at −78° C. under a nitrogen atmosphere, was added n-butyllithium (24.157 ml, 38.651 mmol, 1.6 M in hexanes) dropwise. The resulting reaction mixture was stirred at −78° C. for 45 min. and then a solution of iodine (9.81 g, 38.651 mmol) in dry THF (20 ml) was added dropwise. The mixture was stirred at −78° C. for 1 h. The mixture was allowed to warm to room temperature, diluted with EtOAc and quenched with NH4Cl (aqueous sat. solution) and Na2S2O3 (aqueous sat. solution). The combined organic extracts were separated, washed with NaHCO3 (aqueous sat. solution), dried (Na2SO4) and concentrated in vacuo. The crude product was purified by column chromatography (silica gel; Heptane/DCM up to 20% as eluent). The desired fractions were collected and concentrated in vacuo to yield intermediate compound D5 (7.8 g, 81%).

Provenance & Evidence