1-[Hydroxy(sulfonyloxy)iodo]-1H,1H-perfluoroalkanes: Stable, Fluoroalkyl Analogs of Koser's Reagent.
1-[Hydroxy(sulfonyloxy)iodo]-1H,1H-perfluoroalkanes 3 [R(f)CH(2)I(OH)OSO(2)R; R = CH(3), CF(3), p-CH(3)C(6)H(4), R(f) = CF(3), C(2)F(5)] can be prepared in two steps from the appropriate iodofluoroalkanes by oxidation with peroxytrifluoroacetic acid and subsequent reaction with TsOH, MsOH, or Me(3)SiOTf. The tosylate derivative 3a reacts with silyl enol ethers under mild conditions to give the respective alpha-(tosyloxy) ketones. A similar reaction of cyclohexene furnishes cis-1,2-bis(tosyloxy)cyclohexane as the major product. Triflates 3c,f react with (trimethylsilyl)arenes under mild conditions to afford the respective (fluoroalkyl) (aryl)iodonium triflates 7, while the analogous reaction with alkynyltrimethylsilanes leads to novel (fluoroalkyl)(alkynyl)iodonium salts 8.