Perfluoroalkyl group reaction

Particularly alkyl halides which have a perfluoroalkyl group at the /3-position undergo smooth carbonylation. Probably the coordination of fluorine to form a five-membered chelate ring accelerates the reaction. Double carbonylation to give the a-keto amide 915 is possible in Et NH with the fluorine-bearing alkyl iodide 914[769,770]. The ester 917 is obtained by the carbonylation of the /3-perfluoroalkyl iodide 916 in ethanol. 

Under sonication conditions, the reaction of perfluoroalkyl bromides or iodides with zinc can be used to effect a variety of functionalization reactions [39, 40, 41, 42] (equation 30) Interestingly, the ultrasound promoted asymmetric induction with the perfluoroalkyl group on the asymmetric carbon was achieved by the reaction of perfluoroalkyl halides with optically active enamines in the presence of zinc powder and a catalytic amount of dichlorobisftc-cyclopenta-dienyl)titanium [42] (equation 31)... 

Reactions of fluorinated dipolarophiles. Electron-deficient unsaturated species generally make better dipolarophiles, therefore, fluonnated alkenes become better dipolarophiles when vinylic fluonnes are replaced by perfluoroalkyl groups For example, perfluoro-2-butene is unreactive with diazomethane, but more highly substituted perfluoroalkenes, such as perfluoro-2-methyl-2-pentene, undergo cycloadditions in high yields [5] (equation 2) Note the regiospecificity that IS observed in this reaction... 

Perfluoroalkyl groups adjacent to multiple bond systems lower the frontier molecular orbitals (FMOs) Therefore, cycloaddition reactions preferentially occur with electron-rich multiple-bond systems The preference of bis(trifluoromethyl)-substituted hetero-l,3-dienes for polar reacuons makes them excellent model compounds for developing new types of diene reactions deviating from the well documented Diels-Alder scheme (pathway 1) A systematic study of the reactions of diene (1 =2-3=4)-dienophile (5=6) combinations reveals new synthetic possibilities that have not yet been fully exploited as tools for preparative organic cherrustry (equation 25)... 

Perfluoroalkyl group-containing surfactants like fluoroalkylsuccinamic surfactant and fluoroalkylthio derivatives from the reaction of bis-2-hydroxyethyl-aminomethylphosphonic acid ester with maleic anhydride were especially useful for the preparation of foams for extinguishing burning hydrocarbon liquids. A surface tension of 19.8 mN/m in a 0.1% aqueous solution was observed [88. ... 

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... 

This chapter does not attempt to cover electrochemical processes which involve the insertion of a group already containing carbon-fluorine bonds into an existing molecule (the building block approach), e.g., perfluoroalkyl group insertion via the Kolbe reaction, or fluoroacyloxylations or fluoroalkoxylations via electro-oxidation, or fluoroalkylation via electro-reduction. These have been reviewed elsewhere [1,2]. 

Chlorine monofluoride is capable of oxidizing a sulfur atom bonded to one or two perfluoroalkyl groups through the addition of two or four fluorine atoms to the sulfur atom, depending on the ratio of the reagents and the reaction temperature. 

A mixture of products, that contains regioisomeric bromohydrin acetates, is obtained20 by the bromine/acetic acid oxidation of an alkene having a tertiary perfluoroalkyl group in the allylic position. It is interesting that a different composition of the product mixture 61-63 is obtained depending on the addition of bromine or of the alkene to the reaction mixture.20... 

All of the C = C bond migrations discussed above involve the shift of an atom, usually fluorine. In one case, a perfluoroalkyl group shift has been observed. Chambers and co-workers reported that perfluoro(4,4-dimethylpent-2-ene) (16) isomerizes almost quantitatively to alkcnc 17 when heated with cesium fluoride in sulfolane at 150— 160 C for 5 hours.36 Based on trapping experiments, the authors concluded that the reaction involves an intcrmolccular transfer of a trifluoromethyl anion. 

The isomerization of ra-pentane in superacids of the type RFS03H-SbF5 (RF = C F2 +i) has been investigated by Commeyras and co-workers.93 The influence of parameters such as acidity (A), hydrocarbon concentration (B), nature of the perfluoroalkyl group (C), total pressure (D), hydrogen pressure (E), temperature (F), and agitation has been studied. Only A, C, E, and F have been found to have an influence on the isomerization reaction in accordance with such reactions in the HF-SbFs system. 

Aryl-A3-iodanes bearing an electron-deficient alkyl ligand such as aryl(sul-fonylmethyl)-A3-iodanes (Section 3.2.7) and aryl(perfluoroalkyl)-A3-iodanes are relatively stable. A series of (perfluoroalkyl)phenyl-A3-iodanes 96 were synthesized in good yields by treating bis(trifluoroacetoxy)-A3-iodanes with benzene in the presence of triflic acid [47]. The AModanes 96 transfer the perfluoroalkyl groups to a variety of nucleophiles with reductive elimination of iodobenzene. The nucleophiles involve Grignard reagents, alkyllithiums, enolate anions, alkenes, alkynes, trimethylsilyl enol ethers, arenes, phenols, and thiols. In these reactions, the AModane 96 serves as a source of the perfluoroalkyl cation and, in... 

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