C-X bond activation

Insertion of the C=C bond into an M-H bond precedes frequently the C-X bond activation in halogenated alkenes. Such a pathway has been suggested for the cobalamin-mediated dechlorinations of cis- and trans-DCE, as well as VC with Ti(III) citrate as a reducing agent [141]. 

The first step of the catalytic cycle constitutes the oxidative addition of the organic halide to the Pd catalyst, yielding a c/5-palladium(Il) species, which subsequently isomerizes to the more stable trans form [8]. Theoretical studies so far have focused on the molecular mechanism of C-X bond activation and the influ-... 

Organ, M. G., Arvanitis, E. A., Dixon, C. E., Cooper, J. T. Controlling Chemoselectivity in Vinyl and Allylic C-X Bond Activation with Palladium Catalysis A pKa-Based Electronic Switch. J. Am. Chem. Soc. 2002,124,1288-1294. 

The mechanisms of the two steps in cyclometalation reactions are shown in Eq. (6.7). The first step is metal activation, and the second is the chelate effect. Recently, numerous articles have been pubhshed on agostic interactions, C-H activations (C-H bond activations), C-X activations (C-X bond activations), chelation-assisted reactions, and C-H functionalizations (C-H bond functionalizations). However, many of these articles are concerned with cyclometalation reactions. It is considered that, in the first stage, the metal activation in cyclometalation reactions is related to agostic interactions, C-H activations, and C-X activations and that, in the second stage, the chelate effect is related to chelation-assisted reactions and C-H functionalizations. 

Other terms related to the cyclometalation reactions described above, that is, C-H activations (C-H bond activations), C-X activations (C-X bond activations), chelation-assisted reactions, and C-H functionalizations (C-H bond functionalizations), are employed as title words in article titles, as shown in the following sequence. 

Secondly articles employing C-X activations (C-X bond activations) as title words are shown in Eqs. (6.30)-(6.41). 

Kinetico-Mechanistic Studies on Intramolecular C-X Bond Activation (X=Br, Cl) of Amino-Itnino Ligands on Pt(II) Compounds. Prevalence of a Concerted Mechanism in Nonpolar, Polar, and Ionic Liquid Media... 

In this chapter, the applications of douhle-functionalized arenes in the synthesis of five-memhered heterocycles will he discussed. The eontents are divided according to the different types of substrates applied. The subchapters are organized based on the types of nucleophiles o/t/jo-substituted to aryl halides. For the heterocycle synthesis based on C-X bond activation, in general, transition metal catalyst promoted activation of the C-X bond initiated the reaction sequence and was followed by intramolecular or intermolecular cyclization. 

QUASI-BORINIUM CATION BASED ON COBALT BIS(DICARBOLLIDE) ITS LEWIS ACIDITY AND C-H AND C-X BOND ACTIVATION... 

With an alkyl halide as substrate, C-X bond activation can follow. For example the diiridium system reacts with 1,2-dichloroethane to give Ir2Cl2 and ethylene (eq. 26-8). The first step is thought to be direct atom transfer, although formation of the anion radical of the alkyl halide followed by dissociation to the halide anion and a C-centered radical is in principle a possibility. 

Algarra AG, Macgregor SA, Panetier JA (2013) Mechanistic studies of C-X bond activation at transition-metal centers. In Reedijik J, Poeppelmeier K (eds) Comprehensive inorganic chemistry II, vol 9. Elsevier, Amsterdam, pp 635-694... 

Diefenbach A, De Jong GT, Bickelhaupt FM (2005) Activation of H-H, C-H, C-C and C-Q bonds by Pd and PdCl . Understanding anion assistance in C-X bond activation. J Chem Theory Comput 1 286... 

Copper-catalyzed C—H and C—X bond activations have attracted much attention because they can convert a C—H bond directly into a C—C or C—FG bond. These transformations meet the basic requirements of green chemistry [82], One elegant example of a cascade reaction related with the copper-catalyzed C—H bond activation is the copper-catalyzed C—H oxidation/cross-coupling of indole with a-amino carbonyl compounds (Scheme 5.80). 

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