Difluoroorganometalate-assisted generation of perfluorocarbanions from trimethylsilyl synthons and their interactions with perfluoroaryl compounds

Barbier-type reactions of ICF2CF2OCF2CF2SO2F, I(CF2CF2)(4)OCF2CF2SO2F, and I(CF2CF2)(4)OCF(CF3)(2) with MeMgBr and ClSiMe3 in 3:1 tetrahydrofuran (THF )/diethyl ether mixtures at -78 degrees C gave Me3SiCF2CF2OCF2CF2SO2F (1), Me3Si(CF2CF2)(4)OCF2CF2SO2F (2), and Me3Si(CF2CF2)(4)OCF(CF3)(2) (3) in 65- 89% yields. The anions in three difluorometalates, [(Me2N)(3)S](+)[Me3SiF2] (-) (TASF), [Bu4N](+)[Me3SiF2](-) (TBAT), and [(Pip(2)N)(3)S](+)[Me3SnF2](- ) (TPSF), were reacted with 1-3, to generate 2 equiv of Me3SiF for TASF and TBAF or 1 equiv each of Me3SnF and Me3SiF for TPSF, and the perfluoroalkyl ether nucleophiles -CF2CF2OCF2CF2SO2F, (-)(CF2CF2)(4)OCF2CF2SO2F, and (-)( CF2CF2)(4)OCF(CF3)(2), respectively. The sulfonium or ammonium countercatio n interacted with hexafluorobenzene, monosubstituted pentafluorobenzenes, a nd pentafluoropyridine over a range of temperatures between -78 and 25 degr ees C to also generate aryl carbocationic species that reacted with -CF2CF2 OCF2CF2SO2F to give XC6F4CF2CF2OCF2CF2SO2F, where C-X = C-F (4), C-NO2 (5), C-CN (6), C-CF3 (7), C-CH = CH2 (8), N (9), with (-)(CF2CF2)(4)OCF2CF2SO2F to give XC6F4(CF2CF2)(4)OCF2CF2SO2F, where C-X = C-NO2 (10), C-CN (11), C- CF3 (12), N (13), and with (-)(CF2CF2)(4)OCF(CF3)(2) to give XC6F4(CF2CF2)( 4)OCF(CF3)(2), where C-X = C-F (14), C-NO2 (15), C-CN (16), C-CF3 (17), C-C H=CH2 (18), N (19). The new products were obtained in 22-73% yields, and pu rification was carried out by separation of fractions either by silica gel preparative thin-layer chromatography (TLC) by using a diethyl ether/cycloh exane mixture as the mobile phase eluent (XC6F4(CF2CF2)(4)OCF(CF3)(2) type compounds) or by octadecyl bonded reverse-phase thin-layer chromatography ( rp-TLC) by using an acetonitrile/water mixture as eluent. Reaction of compo und 16 with 2 mol equiv of Me3SiOOCMe resulted in the disubstitution produc t at ortho positions of the nitrile. Compound 5 was transformed via a five- step process to the tricarboxylate o-(MeCOO)(2)O2NC6F4CF2CF2OCF2COOMe (24). The new products were characterized by elemental analyses and NMR and high -resolution mass spectral analysis.