(Pentamethylcyclopentadienyl)iridium(III) Dichloride Dimer

Typical Procedure:
To a 20 mL two-necked flask with a reflux condenser and a rubber cap are added 2-aminobiphenyls (0.5 mmol), [Cp*IrCl₂]₂ (0.01 mmol, 8.0 mg), Cu(OAc)₂ (0.1 mmol, 18 mg), pivalic acid (1 mmol, 102 mg), 1-methylnaphthalene (ca. 30 mg) as an internal standard, and N-methyl-2-pyrrolidone (NMP, 3 mL). Then, the resulting mixture is stirred under air at 120 °C for 3-6 h. After cooling, the reaction mixture is extracted with ethyl acetate (100 mL). The organic layer is washed by aqueous NaHCO₃ (100 mL×3), and dried over Na₂SO₄. After evaporation of the solvents under vacuum, the product is isolated by column chromatography on silica gel using hexane-ethyl acetate (10:1) as the eluent.

Typical procedure: An 8L Hastelloy pressure reactor is charged with the alcohol (2.4 kg), 3-chloro-4-fluorobenzylamine (2.97 kg), (pentamethylcyclopentadienyl)iridium(III) dichloride dimer (3.7 g), 1 N aqueous sodium bicarbonate solution (9.2 mL) and toluene (470 mL). The reactor is purged with nitrogen and then sealed and heated to 110 °C and held for 24 h. The maximum internal pressure during the reaction is 25 psig. After 24 h, an additional charge of the iridium catalyst (1.42 g) and the sodium bicarbonate solution (3.5 mL) is added to the mixture, which is heated to 110 °C for 16 h. The mixture is cooled and diluted with 2-propanol (7.2 L), and distilled under reduced pressure. When the pot volume reached ~7 L, 2-propanol (7.2 L) is added, and distillation is continued, again reducing the volume to ~7 L. After a second dilution with 2-propanol (7.2 L), the mixture is concentrated to 7L, cooled to ambient temperature, and transferred into a reactor containing a preheated (50 °C) solution of 5 N HCl in 2-propanol (9.31 kg, 2.75 eq.). The resulting slurry is cooled to ambient temperature and granulates for 4 h. The resulting product is removed by filtration, washed with 2-propanol (72 L), and dried in a vacuum oven (50 °C, 0.05 bars) to give the desired product (4.81 kg, 76%) as a white crystalline powder (m.p. 232 °C) including 4 ppm of Ir.