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Directed metalation metal-arene complexes

The use of transition-metal arene complexes to facilitate nucleophilic aromatic substitution features in a route to derivatives of thiosalicylic acid and hence to thioxanthone. The cyclopentadienyl iron complex of 2-chlorobenzoic acid is converted into the benzamide prior to displacement of the chloride by thiophenoxide. Photolytic decom-plexation followed by directed remote metallation of the diaryl sulfide yielded the heterocycle (Scheme 207) <2000SL975>. [Pg.906]

The Fischer-Hafner synthesis of sandwich compounds (33) does not permit functional groups to be incorporated into the arenes because of side reactions with the Lewis acid catalyst (Friedel-Crafts reducing conditions). This is not the case when metal atoms are used directly. Many metal-arene complexes have been identified that contain F, Cl, CH30, R2N and C02R substituents. It is reasonable to assume that polymer-bound phenyl substituents containing these functional groups will yield similar sandwich complexes. [Pg.248]

Furthermore, ir-arene complexes of transition metals are seldom formed by the direct reaction of benzene with metal complexes. More usually, the syntheses require the formation of (often unstable) metal aryl complexes and these are then converted to ir-arene complexes. The analogous formation of w-adsorbed benzene at a metal surface via the initial formation of ff-adsorbcd phenyl, merits more consideration than it has yet been given. It is to be hoped that the recognition and study of structure-sensitive reactions will allow more exact definition of the sites responsible for catalytic activity at metal surfaces. The reactions of benzene, using suitably labeled materials, may prove to be useful probes for such studies. [Pg.154]

The indazoline products can also be made directly from the palladium complexes 78 by heating them with the isonitrile in toluene at 120CC.162 They are also formed in dicobalt octacarbonyl-catalyzed reactions of azo-arenes with isocyanides but in this case an alternative reaction pathway leading to indazolo[2,l- ]indazoles (79) is observed (Scheme 96).163 Products of the latter type are formed from sterically hindered isocyanides hence it is likely that in these cases a double metallation is favored over isocyanide insertion into a monometallated species (Scheme 97). [Pg.361]

Three methods are commonly employed for the in situ preparation of organopalladium derivatives (i) direct metallation of an arene or heterocyclic compound with a palladium(II) salt (ii) exchange of the organic group from a main group organometallic to a palladium(II) compound and (iii) oxidative addition of an organic halide, triflate or aryldiazonium salt to palladium(O) or a palladium(O) complex. [Pg.834]

Support for this step was obtained by us in experiments where M was shown to add directly to bis(arene)metal complexes to give M2L2 (45, 46). Maximum nuclearity and stability of these species depends on the element, atom deposition rate, temperature and the type of arene. Mono-alkyl and -silyl substituted arenes give compounds that are unstable above 0 C. On the other hand, single crystals of a related triple-decker sandwich of mesitylene and chromium have been obtained (47),... [Pg.250]

Orthometallation of substituted arenes has been re-viewed. The ortho-directing ability of substituents in ( ) -arene)Cr(CO)3 complexes decreases as F > CONHR > NHCOR > CH2NR2 OMe CH20Me. Heavier alkali metal arenes can be formed from the reaction of phenyl lithium with sodium or potassium aUcoxides. [Pg.89]

The cocondensation of transition metal atoms and aromatic hydrocarbon at liquid nitrogen temperature leads directly to zero-valent arene complexes (27, 288, 376). Complexes, such as (CgHg)2Ti and (CgFg)-(CgHg)Cr, that are not accessible by the Fischer-Hafner method have been prepared by this method. [Pg.49]

The direct reaction between a metal carbonyl and an aromatic hydrocarbon often leads to the replacement of 2 or 3 carbonyl groups yielding arene complexes. Complexes of the type [(arene)V(CO)4][V(CO)g] 50), (arene)Cr(CO)g 327), and (arene)Fe(CO)3 281) have been prepared in this manner. Carbonyl metal halide complexes have also been observed to react with aromatic hydrocarbons in the presence of AlClg yielding cationic arene derivatives, e.g. 71, 104, 448),... [Pg.49]


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Arene complexe

Arene complexes

Arenes complexes

Arenes metal complexes

Arenes metalation

Arenes metalations

Arenes metallation

Complexation direction

Direct metalation

Direct metallation

Metal arene

Metal arenes

Metal-arene complexes

Metalated arenes

Metalation arene

Metallation directed

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