Silver catalysis aromatization

Tsunoyama H, Sakurai H, Tsukuda T (2006) Size effect on the catalysis of gold clusters dispersed in water for aerobic oxidation of alcohol. Chem Phys Lett 429 528 Pradhan N, Pal A, Pal T (2002) Silver nanoparticle catalyzed reduction of aromatic nitro compounds. Colloids Surf A 196 247... 

Phenyl acetylene and acetophenone are also the reaction products observed when /3-bromostyrene is solvolysed in aqueous ethanol at 100°C . This reaction is also strongly accelerated by electron-releasing aromatic substituents but electron-withdrawing substituents render the substrates almost inert. The possibility that the ketone arises from the addition of water to the olefin followed by an Eco reaction (see Section 4.3) seems unlikely, as the rate of solvolysis is not influenced by varying the concentration of added triethylamine although this reagent induces bimolecular elimination from the strongly acidic p-nitro substrate. Moreover, as silver-ion catalysis is observed, it seems that the mechanism is of the El type, (214). 

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. " ... 

The arylation of polyfluoroarenes has also been achieved with Pd/Ag catalysis (Scheme 22.43a) [61c]. Mechanistic investigations have demonstrated that the Pd-phosphine complex and the silver salts are both involved in the decarboxylation of electron-rich aromatic acids (Scheme 22.43b ... 

It was demonstrated that BINOL catalysts authorize the /3- and /-functionalizations of the allyltin reagents without lowering the enantioselectivity level [223], and such a strategy was used in the total syntheses of macrolides [224] or substituted tetrahydropyran units [225]. It was noteworthy that the BINOL-Ti catalysis was extended to the enantioselective allylation of alkyl and aromatic ketones in good yields with up to 96% ee [226]. Silver/BINAP was used as well, with a marked anti selectivity, when using crotyltins whatever is the nature, (E) or (Z) of the double bond [227]. This reaction was extended to other organometallics such as 2,4-pentadienylstannanes [228] or buta-2,3-dienylstannanes [229] (Scheme 6.26). 

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