Copper-mediated Aromatic Perfluoroalkylation

1 Copper-mediated Trifluoromethylation of 36 Using Silane Reagents 

A mixture of 36 (0.5 mmol), Et3SiCp3 (0.6 mmol), Cul (0.75 mmol), KF (0.6 mmol), and DMF/NMP (1 1) (1 mL) was heated in a sealed Pyrex tube to 80 °C for 24 h. After cooling the tube was opened with the usual safety precautions and the contents were subjected to an aqueous work-up. Compound 37 was obtained in 99% yield with minimal contamination by its pentafluoroethyl analog [20]. 

Similar results can be achieved by use of Me3SiCp3 (Rupperfs Reagent) [21]. When Me3SiC2p5 or Me3Si-n-C3p7 are used instead (in DMF at 60 °C for 24 h), the pentafluoroethyl (40) or perfluoropropyl arenes (38) are obtained in reasonable to good yields [20]. 

Trifluoromethylthio copper(I) (43) (0.47 g, 2 mmol), 4-iodoanisole (44) (1.55 g, 10 mmol), and NMP (10 mL) were placed in a 25-mL round-bottom flask and heated at 150 °C for 18 h. The resulting black solution was left to cool. Water was then added and the organic products were extracted twice into diethyl ether. The ether extracts were combined and washed three times with water. The ether was removed by rotary evaporation to yield 0.21 g product 45 (45 %) [23] NMR (CDCI3) d = -44.4 (s) MS (El) m/z (%) = 208 [M+] (60), 139 (100). 

---