Silver carbon-hydrogen bonds

Copper and silver complexes bearing trispyrazolylborate ligands have shown catalytic activity towards several organic transformations involving the functionalization of unsaturated carbon-carbon bonds or several saturated E—H bonds, particularly of carbon-hydrogen bonds. The tunability of this class of ligands from both steric and electronic perspectives allows the control of those catalytic capabilities. On the basis of the work already described, the potential for their use on other, yet unreported transformations seems feasible. 

Silver derivatives containing Tp(CF 2 catalyze the carbene insertion into carbon-hydrogen bonds of cyclic and acyclic hydrocarbons at room temperature. [Ag(Tp CF3 2)(THF)] is more effective... 

The exit gas from the generator ice trap is dissolved directly in water. The hydrogen-ion concentration of the resulting solution is determined by titration with standard base, and the iodide-ion concentration by the precipitation of silver iodide. Only traces of tetrahydronaphthalene are detected by the very slight carbon-hydrogen bond-infrared absorption in the samples of the anhydrous gas prepared by this procedure. 

Regioselective functionalization of unreactive carbon-hydrogen bonds, in particular, arylation of pyridines by using aryl iodide, silver acetate, and catalytic palladium acetate 06SL3382. 

The possibilities for the formation of carbon—carbon bonds involving aromatic compounds have been enormously enhanced by the use of transition metal catalysts, and this area has been the subject of several reviews. Some of these concentrate on the applications of specific metals, and there have been surveys of the use of compounds of silver, copper and nickel,mthenium, and palladium in catalysis. The metalation of carbon-hydrogen bonds, preceding functionalization, may be aided by carboxylate ions, and this subject has also been reviewed. There is evidence here for concerted base-assisted deprotonation as shown in (10). In the carboxylate-assisted reaction of aryl ketimines with alkyl halides, a ruthenium-bonded intermediate (11) has been proposed, which subsequently adds the alkyl halide. " ... 

Activation of carbon—hydrogen bonds in benzyl phenyl sulfoxides catalysed by palladium may lead to dibenzothiophene derivatives (39). lodoarenes and silver salts are required as additives, and product formation requires several consecutive catalytic cycles. The copper-catalysed conversion of bisaryloxime ethers to 2-arylbenzoxazoles is likely to involve complexation of the catalyst at... 

There has been a summary of computational and experimental studies of the use of palladium complexes with A -heterocyclic carbenes (NHCs) in the asymmetric coupling of -hybridized carbon-hydrogen bonds with aryl halides. It has been shown that the electronic and catalytic properties of NHCs fused to porphyrins may be modified by varying the inner metal in the porphyrin. A DPT study of the use of palladium-NHC complexes in the asymmetric intramolecular a-arylation of 2-bromoaryl amides to give 3,3-disubstituted oxindoles (101) has been reported. The likely pathway involves insertion of the palladium into the arene-bromine bond to form a palladacycle which deprotonates to give an (9-enolate. Conversion into the C-enolate followed by reductive elimination gives the product. The intramolecular reaction of 0 a cyclopropane carbon-hydrogen bond in a 2-bromoanilide derivative has been used to form cyclopropyloxindoles, (102), in a palladium-catalysed, silver-mediated reaction. 

Olefin Complexes. Silver ion forms complexes with olefins and many aromatic compounds. As a general rule, the stabihty of olefin complexes decreases as alkyl groups are substituted for the hydrogen bonded to the ethylene carbon atoms (19). 

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