In a typical procedure, Cu 2 O (0.05 mmol) was mixed with the commercially available perfluorinated acid C 11 F 23 COOH (0.1 mmol) in HFIP (1.5 mL) to ensure its complete solubility. The solution took rapidly a deep blue colour. Olefin (5 mmol) and t-BuOOC(O)Ph (1 mmol) were then ...