Fluorodienes

Like simple elemental halogens, iodine monochloride reacts with conjugated fluorodienes to yield mostly 1,4-addition products. These bidirectional reactions lead to mixtures of regioisomers, as shown in Table 5 [//]. 

Table 5. Reactions of Iodine Chloride viith Fluorodienes in Methylene Chloride at -S C under Argon [ll ...

When position 4 of perfluoropyridine is blocked with a poor leaving group, ammonia replaces the fluonne in position 2 in good yield. Oxidation of the products obtained with hypochlorite, followed by lodme-catalyzed rearrangement, yields interesting fluorodienes [78] (equation 41) Ultraviolet irradiation can be used to assist reactions m which substitution is difficult [79]... 

The synthesis of chlorotrifluorobutadiene illustrates a general method that has been used to make tetrafluorobutadiene and substituted fluorodienes.3- 9 The same procedure can be used to transform fluorocyclobutenes and chlorofluorocyclobutenes to the isomeric dienes 2-methyl-1,1,4,4-tetrafluorobutadiene, 2-chloro-l,l,4,4-tetrafluorobutadiene, and l-chloro-l,4,4-trifluoro-2-phenylbutadiene have been made thus.3... 

New and Revisited Transition Metal Chemistry of Fluoro-Olefins and Fluorodienes ... 

In an analogous way, fluorodienes can be prepared. The substrates for this reaction may be the disodium salts of fluorocarboxylic acids, but unsaturated fluorocarboxylic acids can also be converted to fluorodienes by the sodium salt reaction. e.g. formation of perfluorobuta-1,3-diene (6) from either disodium perfluorohexanedioate or sodium perfluoropcnt-4-enoate. ... 

Polyfluoroalkanes, Polyfluoroalkenes, Polyfluoroalkynes and Derivatives 215 Table 7.16 Synthesis of fluorodienes and polymers... 

Isomerization of perfluoroalkenes can be realized by use of SbFs catalysis [37]. The terminal carbon-carbon bonds of these alkenes are usually moved to the 2-position under the influence of this catalyst (Eq. 19). A further inward shift generally occurs only if H or Cl atoms are present at the 4-position of the alkenes. As a rule, isomerization leads to the predominant formation of trans isomers. Terminal fluorodienes also isomerize exothermally into dienes containing internal double bonds in the presence of SbFj. With a catalytic amount of SbFs, perfluoro-l,4-cyclohexadiene disproportion-ates to hexafluorobenzene and perfluorocyclohexene. SbFs promotes the rearrangement of perfluoroepoxides to carbonyl compounds (Eq. 20) [38]. 

Reduction of acetoxy difluorocyclopropanes with lithium aluminium hydride allows preparation of ) -fluoroalcohols (equation 140) , whereas deprotonation of difluorocyclopropanes bearing an acceptor-substituted side chain gives fluorodienes stereoselectively after cyclopropylmethylanion-homoallyl anion rearrangement and fluoride elimination (equation 141) . ... 

Terminal gem-difluoro-substitution affects the rate of some reactions in a steric manner. Scheme 1.78 shows thermal Cope rearrangement of the particular bis-difluorodienes (10) (d, l) and (11) (meso), where the activation enthalpies of fluorodienes (X= F) are compared with those of the corresponding hydrocarbons (X = H). For the d, l-isomers, fluoroalkene 10 reacted faster with the lower activation enthalpy than did the corresponding hydrocarbon 10 (X = H) (Scheme 1.78). The rearrangement of 10 would proceed via chair-like... 

Chlorofluorocarbene. Schlosser et al. have found that this crown ether is significantly superior to the commonly used ammonium salts for generation of chlorofluorocarbene from dichlorofluoromethane by the two-phase technique. They used potassium hydroxide as base rather than sodium hydroxide, since crown ethers bind potassium ions more selectively than sodium ions. They used the carbene for synthesis of fluorodienes. The method is illustrated for the conversion of methallyl chloride (1) into 2-fluoro-3-methyl-l, 3-butadiene (3-fluoro-isoprene), (4). The conversion of (3) into (4) involves a 1,4-elimination of ICl ... 

Fluorocarbene, 261 a-FIuorocarboxylic acids, 473 Fluorocyclopiopanes, 261 Fluorodehydroxylation, 560 Fluorodienes, 175 Fluorodilodomethane, 261-262 Fluorodimethoxyborane, 261-262 6-Fluoro-4,4-dimethylcyclohexene-2-one-1,263... 

Dihydrothiophendioxide 122 adds CIF (generated from HF and A -chlorosuc-cinimide) giving tetrahydrothiophene-1,1-dioxide 123 used as a starting material for the synthesis of 3-chloro-4-fluorothiophene-1,1-dioxide 124. Compound 124 can be used in organic synthesis as fluorodiene. "... 

Tetrakis(trifluoromethyl)thiophene 161 was synthesized by the reaction of per-fluorodiene with potassium sulhde or by exhaustive trifluoromethylation of tetra-iodothiophene using trifluoromethyl copper ... 

Dmowski, W. Manko, V.A. Nowak, I. 3-Chloro-4-fluorothiophene-l,1-dioxide. A new synthetically useful fluorodiene. J. Fluorine Chem. 1998, 88, 143-151. 

Mouttaki H, Nanny MA, Mclnerney MJ. Metabolism of hydroxylated and fluorinated benzoates by Syntrophus aciditrophicus and detection of fluorodiene metabolite. Appl Environ Microbiol. 2009 75 998-1004. 

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