Iodomesitylene Diacetate

Preparation of Iodomesitylene Dicarboxylates: Iodomesitylene diacetate (10 mmol), cyclohexyl carboxylic acid (20.5 mmol), and toluene (200 mL) are placed in flask. The solvent is removed by a rotary evaporator at 55 °C. This step is repeated with toluene (100 mL) as needed. The residue is concentrated in vacuo, to provide iodomesitylene dicarboxylates that can be directly used in the decarboxylative sp³ C–N coupling reactions without further purification.

sp³ C–N Coupling Reaction: Ir(F-Meppy)₂(dtbbpy)PF₆ (4.9 mg, 5.0 µmol), copper(I) 2-Thiophenecarboxylate (19 mg, 0.10 mmol), bathophenanthroline (50 mg, 0.15 mmol), 2-tert-butyl-1,1,3,3-tetramethylguanidine (0.21 mL, 171 mg, 1.0 mmol), 3-chloro-1H-indazole (76 mg, 0.50 mmol), iodomesitylene dicyclohexanecarboxylate (500 mg, 1.0 mmol), and 1,4-dioxane(12 mL) is placed in vial. The solution is sonicated until it becomes homogeneous and is then degassed with nitrogen. The reaction is stirred and irradiated using two 34-W blue LED lamps for 1 h. After the reaction has completed, the reaction mixture is diluted with water and EtOAc. The aqueous layer is extracted with EtOAc. The combined organic layers are washed with brine, dried over Na₂SO₄, filtered and concentrated in vacuo. The residue is purified by flash chromatography (30:1 hexane/EtOAc) on silica gel to afford the title compound (99 mg, 84% yield, >20:1 r.r.) as a colorless oil.