synthesis of diaryliodonium tetrafluoroborates 3r-w from 8: To a solution of (diacetoxyiodo)arene 8 (1.0 equiv) in CH2Cl2 [0.05 M] at -78 °C, BF3•OEt2 (2.5 equiv) was added dropwise and the reaction was allowed to stir for 15 min. Then the corresponding boronic acid 4 (1.2 equiv) was added in one portion, and the reaction was allowed to reach rt and stirred for 1 h. The reaction mixture was filtered over a short silica column and eluted with a 5:1 CH2Cl2/MeOH mixture. The solvent was evaporated to dryness and the product 3 was precipitated in Et2O and isolated by filtration. If product precipitation is difficult: Stir the product in Et2O overnight at rt to achieve full precipitation. In situ anion exchange to triflate (3s-3u): the CH2Cl2 was evaporated under a steam of air, and the residual crude tetrafluoroborate salt was dissolved in MeCN [0.05 M] and treated with TfOH (1.2 equiv). The reaction was stirred for 30 min, followed by evaporation to dryness. Product 3 was triturated with diethyl ether and isolated by filtration.