Tricyclohexylphosphonium Tetrafluoroborate

Siteselective phenylation of 3-nitrophenylsulfur pentafluoride:
A 25 mL Schlenk tube equipped with a magnetic stir bar is charged with (allylPdCl)₂ (2.5 mol%), PCy₃・HBF₄ (7.5 mol%), and K₂CO₃ (1.8 equiv.). The reaction tube is evacuated and backfilled with N₂ (4 times), then 2,2-dimethylbutyric acid (0.3 equiv.), bromobenzene (1.5 equiv.), toluene (0.8 mL) and 3-nitrophenylsulfur pentafluoride (0.5 mmol, 1.0 equiv.) are added subsequently. The sealed tube is screw capped and heated to 130 °C for 15h. The reaction vessel is then cooled to room temperature, and the reaction mixture is concentrated in vacuo directly. The resulting residue is purified with silica gel chromatography to afford 2-nitro-[1,1'-biphenyl]-4-yl sulfurpentafluoride in 79% yield.

Typical procedure: Pd₂(dba)₃ (4.6 mg), Cy₃PHBF₄ (7.4 mg) and N,N-diisopropylethylamine (5.2 mg) are added to toluene (10 mL) and resulting mixture is stirred at rt for 10 min. 10-Undecyn-1-ol (168 mg) is added and then Bu₃SnH (349 mg) diluted in toluene (3 mL) is added dropwise over 5 min. The reaction is then allowed to stir at rt for 2 h. The reaction mixture is concentrated and purified by silica gel chromatography (eluent: hexanes/ether = 8/1 to 5/1) to give the corresponding vinylstannane (399 mg, 87 %).