Activation of carbon-fluorine bonds

Oxidative addition of C-F bonds to low-valent metal complexes constitute one of the routes in activation of fluoroalkanes and fluoroarenes [71, 72], The chemical activation of carbon-fluorine bonds has attracted much attention since functionalization of C-F compounds gives various fluoroorganic derivatives, which have many technological applications. Typical examples of oxidative addition of C-F bonds [73] are shown in Scheme IV.36. 

A different approach to the activation of carbon-fluorine bonds involves the formation of HF when using metal hydrides as starting compounds. For instance, the reaction of m-[Ru(H)2(dmpe)2] (dmpe = bis(dimethylphosphino)ethane) with hexafluorobenzene at —78 °C yields /ra / .y-[Ru(H)(C6F5)(dmpe)2] (Scheme There is considerable evidence that this reaction proceeds via an electron-transfer pathway, but this mechanism should not be generalized. 

Activation of Carbon—Fluorine Bonds by Oxidative Addition to Low-Valent Transition Metals... 

OSTERBERG AND RICHMOND Activation of Carbon—Fluorine Bonds 393... 

AB (x = 5 or 6), geometries, 56 Acetylenes, addition of SF halides, 136 Activation of carbon-fluorine bonds conditions, 400... 

Richmond TG (1999) Metal Reagents for Activation and Functionalization of Carbon-Fluorine Bonds. 3 243-269... 

Ribaudo F, van Leeuwen PWNM, Reek JNH (2006) Supramolecular Dendritic Catalysis Noncovalent Catalyst Anchoring to Fimctionalized Dendrimers. 20 39-59 Richmond TG (1999) Metal Reagents for Activation and Functionalization of Carbon-Fluorine Bonds. 3 243-269... 

One of the major activities of chemists in industry and academia is the search for special-effect chemicals, i.e. systems with new chemistry and with novel properties that can be exploited by industry. There are, of course, many ways of creating novel systems but the introduction of carbon-fluorine bonds into organic compounds has led to spectacular industrial developments, together with an exciting field of organic chemistry and biochemistry. 

Two years later, Schaub and Radius showed that dimeric complex [(IiPr2)4Ni2(COD)] also exhibited an interesting reactivity towards C-F bonds. This catalyst activated the carbon-fluorine bond of hexa-fluorobenzene producing a new complex result of oxidative addition (Equation (10.3)). However, this reaction only worked with strongly activated substrates i.e. hexafluorobenzene, octafluoronaphtalene). 

Organic fluorine compounds were first prepared in the latter part of the nineteenth century. Pioneer work by the Belgian chemist, F. Swarts, led to observations that antimony(Ill) fluoride reacts with organic compounds having activated carbon—chlorine bonds to form the corresponding carbon—fluorine bonds. Preparation of fluorinated compounds was faciUtated by fluorinations with antimony(Ill) fluoride containing antimony(V) haUdes as a reaction catalyst. 

Hydrolytic cleavage of single carbon-fluorine bonds generally requires activation by a neighboring group such as a carbonyl, sulfonyloxy, or olefinic bond or a negatively substituted aromatic group. 

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