GENERAL STEPS: In a FEP or PFA reactor fitted with a PTFE-lined magnetic stirring bar and connected to a gas scrubber bottle, substituted benzene (0.95-1.10 mmol), 1,1,1,3,3-pentafluorobutane (2 ml per ml of C6H5R), and BF3-Et2O (1.3-1.5 mmol per mmol C6H5R) were added. The mixture was stirred at 0-5 °C (ice bath) for 10-15 min, followed by batchwise addition of XeF2 (1.2-1.3 mmol per mmol C6H5R). After each addition, the mixture was stirred at 22-25 °C for 3-5 min and cooled to 0-5 °C again. After the addition was completed, the dark colored solution was continued to be stirred at 22-25°C for 15-30 minutes. At the end of the reaction, the reaction was quenched by the addition of 10% aqueous KHCO3, the upper organic layer was separated and filtered through a short column packed with silica gel (40-60 μm). The organic layer was dried with magnesium sulfate and analyzed by 19F NMR and GC/MS. The major products are listed in the table and the others are as follows (GC/MS data).