2-(Diisopropylsilyl)pyridine

To a solution of aryl bromide or -iodide (10 mmol) in THF (15 mL) is added dropwise a solution of n-butyllithium (3.86 mL, 2.59 M in hexanes, 10 mmol) at -78 °C under argon atmosphere. The reaction mixture is stirred at -78 °C for 15 – 40 min and then neat 2-(diisopropylsilyl)pyridine (1.934 g, 10.0 mmol) is added dropwise. The resulting solution is stirred at -78 °C for 1 h and then is allowed to warm to -30 °C. Upon completion of the reaction, the mixture is poured into 150 mL of hexanes containing small amount of water to neutralize LiH. The resulting solution is dried over anhydrous sodium sulfate, filtered, and concentrated under a reduced pressure. The residue is purified by flash column chromatography (silica gel, eluent: EtOAc/Hexanes = 1/10 –1/2) to provide aryl pyridyl silane.

An oven dried 10 ml Wheaton V-vial, containing a stirring bar, is charged with 2-(diisopropyl(aryl)silyl)pyridine (0.5 mmol), Pd(OAc)₂ (11.2 mg, 0.05 mmol), PhI(OAc)₂ (241.6 mg, 0.75 mmol), and NXS (1.0 mmol) under N₂ atmosphere. Dry DCE (5 mL) is added and the reaction vessel is capped with pressure screw cap. Reaction mixture is heated at 60 – 70 °C for 45 min – 4 h until judged complete by GC/MS analysis. The resulting mixture is cooled down to room temperature and filtered through a layer of silica gel with the aid of EtOAc. The filtrate is concentrated under a reduced pressure and the residue is purified by column chromatography on a silica gel (eluent: hexanes/EtOAc = 1/10 – 1/2) affording the corresponding halogenated product.