Perfluoroalkyl complexes

Several cationic 7r-cyclopentadienylcobalt derivatives have been prepared. Treichel and Werber (235, 236) have produced a number of perfluoroalkyl complexes [CpCo(CO)LRF]+CI04-, where L = PPh3, CH3CN, py and Rf= C2F5, C3F7. The stability of these cations approximately parallels the... 

In many cases, CO insertion reactions have been shown to be thermodynamically unfavorable. In these cases, de-insertion of CO occurs. For example, acetyhnetal complexes do not imdergo insertion to form stable a-dicarbonyl compounds. Instead, a-dicarbonyl compoimds de-insert CO to form metal-acyl complexes and free CO (Equation 9.27)P Likewise, the carbonylation of perfluoroalkyl transition metal complexes is usually uphill thermodynamically. Decarbonylation of perfluoroacetyl complexes is one method to prepare perfluoroalkyl complexes (Equation 9.28). ... 

Further perfluoroalkyl complexes of the type RfFc(CO) J [Rf = (CF )tCF or n-C,Fi5] have been described. They are conveniently converted to CpFe(CO>2Rr by cyclopentadienylthallium. Chelating ditertiary phosphines will displace two moles of carbon monoxide, and the ligand CHg C(CH2-PPh2)3 behaves as a bidentate ligand with the iodo-compounds. The anion CpFe(CO)a- reacts with hexafluoroacetone to give the complex (CF3)2C(OH)-Fe(a))gCp. ... 

A more efficient agent than peroxy compounds for the epoxidation of fluoro-olefins with nonfluonnated double bond is the hypofluorous acid-acetomtrile complex [22] Perfluoroalkylethenes react with this agent at room temperature within 2-3 h with moderate yields (equation 13), whereas olefins with strongly electron-deficient double bond or electron-poor, sterically hindered olefins, for example l,2-bis(perfluorobutyl)ethene and perfluoro-(l-alkylethyl)ethenes, are practically inert [22] Epoxidation of a mixture of 3 perfluoroalkyl-1-propenes at 0 C IS finished after 10 mm in 80% yield [22] The trifluorovinyl group in partially fluorinated dienes is not affected by this agent [22] (equation 13)... 

Allylation of perfluoroalkyl halides with allylsilanes is catalyzed by iron or ruthenium carbonyl complexes [77S] (equation 119) Alkenyl-, allyl-, and alkynyl-stannanes react with perfluoroalkyl iodides 111 the presence ot a palladium complex to give alkenes and alkynes bearing perfluoroalkyl groups [139] (equation 120)... 

Codeposition of silver vapor with perfluoroalkyl iodides at -196 °C provides an alternative route to nonsolvated primary perfluoroalkylsilvers [272] Phosphine complexes of trifluaromethylsilver are formed from the reaction of trimethyl-phosphme, silver acetate, and bis(trifluoromethyl)cadmium glyme [755] The per-fluoroalkylsilver compounds react with halogens [270], carbon dioxide [274], allyl halides [270, 274], mineral acids and water [275], and nitrosyl chloride [276] to give the expected products Oxidation with dioxygen gives ketones [270] or acyl halides [270] Sulfur reacts via insertion of sulfur into the carbon-silver bond [270] (equation 188)... 

Perfluoroalkyl or -aryl halides undergo oxidative addition with metal vapors to form nonsolvated fluonnated organometallic halides and this topic has been die subject of a review [289] Pentafluorophenyl halides react with Rieke nickel, cobalt, and iron to give bispentafluorophenylmetal compounds, which can be isolated in good yields as liquid complexes [290] Rieke nickel can also be used to promote the reaction of pentafluorophenyl halides with acid halides [297] (equation 193)... 

Aminopyridines can be perfluoroalkylated in a photoinduced electron transfer process. A charge transfer complex between the heterocycle and polyfluoroalkyl iodide, observable by NMR, is photolytically stimulated... 

Perfluoroalkyl carbanions, generated by reversible nucleophilic addition of a fluoride anion to fluoroalkenes, react with dry benzenediazonium chloride in dimethyl formamide, giving phenylazoperfluoroalkanes in 41-53% yield (Dyatkin et al., 1972). The dianion obtained from 1,2-dinitrobenzene with dipotassium cyclo-octatetraenide reacts in a complex way with arenediazonium salts, forming 4-aryl-azo-2-nitrophenol in 46-58% yield (Todres et al., 1988). 

As outlined above, immobilization in a fluorinated liquid phase demands the functionahzation of the ligand with perfluoroalkyl chains and, even then, the solubihty is strongly influenced by the nature of the complex. Ionic hquids of the alkylmethyhmidazolium type (Fig. 4) have been recently developed as alternative solvents for organometallic catalysis and have the practical advantage of using directly the commercially available chiral hgands and complexes. 

Perfluoroalkyl)-5 -deoxy-5 -fluoro- and 5-(perfluoroalkyl)-2, 5 -di-deoxy-5 -fluoro-uridines were prepared " from 840 and 834, respectively, using perfluoroalkyl-copper complexes. Among them, 5 -deoxy-5 -fluoro-(846) and 2, 5 -dideoxy-5 -fluoro-5-(perfluoroethyl)uridine (839) were particularly effective against Ehrlich ascites carcinoma. 5-Hydroxyl (847) and 5-amino or 5-alkylamino (5-NHMe, -NHBu, -NHCH2Ph, -morpholino, -piperidino, and -pyrrolo) analogs (848) of 840 were prepared. The a anomer of 5 -deoxy-5 -fluorouridine (840) was also synthesized. "... 

Fig. 4 Halogen-bonded adducts are pre-reactive complexes, which, under convenient conditions, can lead to covalent bonds breaking and forming. Perfluoroalkylation occurs when the complexes between iodoperfluoroalkanes and anilines are heated or irradiated in certain solvents...

The structure and packing of the complex with n = 8 and m = 3 are shown in Figs. 14 and 15, respectively (d -i = 2.746 A N- T-C = 176.99°). The former shows an expected disposition of the stilbazoles and the perfluoroalkyl entity, while the latter shows an effective segregation of the fluoro alkyl and stilbazole segments. 

The development of synthetic methods for the selective introduction of short-chain perfluoroalkyl groups into organic molecules is of interest in drug development [464]. Fluoromodifications often confer unique properties on a molecule, for example in terms of increased metabolic stability and lipophilicity and, as a consequence, the pharmacokinetic profiles are often improved [465]. Burger and coworkers developed a domino process consisting of a SN reaction combined with a Claisen and a Cope rearrangement which allows the transformation of simple fluorinated compounds into more complex molecules with fluoro atoms [466]. Treatment of furan 2-917 with 2-hydroxymethyl thiophene (2-918) in the presence... 

Neutral b/.v(acyl)Fe(CO)4 complexes have been reported by Stewart et al. (23). The acyl ligands have perfluoroalkyl substituents. These complexes are isoelectronic to the anionic diacyltetracarbonylmanganate species mentioned above. 

The formation of relatively ill-defined catalysts for epoxide/C02 copolymerization catalysts, arising from the treatment of ZnO with acid anhydrides or monoesters of dicarboxylic acids, has been described in a patent disclosure.968 Employing the perfluoroalkyl ester acid (342) renders the catalyst soluble in supercritical C02.969 At 110°C and 2,000 psi this catalyst mixture performs similarly to the zinc bisphenolates, producing a 96 4 ratio of polycarbonate polyether linkages, with a turnover of 440 g polymer/g [Zn] and a broad polydispersity (Mw/Mn>4). Related aluminum complexes have also been studied and (343) was found to be particularly active. However, selectivity is poor, with a ratio of 1 3.6 polycarbonate polyether.970... 

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