Synthesis, Properties, and Reactivity of (1H,1H-Perfluoroalkyl)- and (1H-Perfluoro-1-alkenyl)aryliodonium Triflates and Their Analogs

Article abstract of DOI:10.1246/bcsj.60.3307

(1H,1H-Perfluoroalkyl)phenyl- and -(p-fluorophenyl)iodonium triflates, fluorosulfate, sulfate (3)-(7) were synthesized in good yields by the oxidation of 1-iodo-1H,1H-perfluoroalkanes (RfCH2I) with trifluoroperacetic acid followed by treatment with triflic acid and benzene or fluorobenzene. (1H,1H,5H,5H-Perfluoropentane-1,5-diyl)bisphenylbisiodonium triflate was synthesized similarly. (trans-1H-Perfluoro-1-alkenyl)phenyliodonium triflates (11) were synthesized by dehydrofluorination of 3 with a base in good yields.Thermolysis of 3 produced 1H,1H-perfluoroalkyl triflate and iodobenzene, while 11 gave (Z)-1-iodo-1H-perfluoro-1-alkene and phenyl triflate.The thermolysis experiment, including (perfluoroalkyl)phenyliodonium triflate (17), demonstrated that the C-I bond strength of the trivalent iodine compounds increased in the order of RfCH2-I < Rf-I < Ph-I < RfCF=CH-I.The ionic mechanism containing RfCH2⁺, Ph⁺, and Rf⁺ for the thermal decomposition of 3, 11, and 17, respectively, was proposed.The reactivities of 3 and 11 to such nucleophiles as phenoxide, alkoxide, and alkanethiolate anions were studied and compared with that of 17.Remarkable changes in the reactivity were found depending on the nature of the fluoro-alkyl and -alkenyl groups.The reaction of 11 with the oxide anions yielded (2-phenoxy- and -alkoxy-1H-perfluoro-1-alkenyl)phenyliodonium triflates.