Deprotonative metallation

Modified Marcus Parameters for Proton-Transfer Reactions with Deprotonated Metal Peptide Complexes... 

The difference between the simple and the complex salts lies in the capability of the ions to deprotonate the water molecules associated with them. For simple ions this is not probable. The hydrolyzed and deprotonated metal cations form multinuclear complexes through oxolation-olation reactions discussed below. These reactions are dependent, not only on the pH, but also on the total metal concentration. By using the conditional constant approach this is illustrated as the dependency of log a(Fe(OH)) plotted as a function of the pH for a range of concentrations of Fe + ions in Figure 8.12. ... 

Scheme 31 Concerted deprotonation/metalation with (HA)SPO preligands...

Acetic add, frons-cyclohexanediaminetetra-metal complexes, 554 Acetic add, ethylenediaminetetra-in analysis, 522 masking, 558 metal complexes, 554 Acetic acid, iminodi-metal complexes, 554 Acetic acid, nitrilotri-metal complexes titrimetry, 554 Acetoacetic add ethyl ester bromination, 419 Acetone, acetyl-deprotonation metal complexes, 419 metal complexes reactions, 422 Acetone, selenoyl-liquid-liquid extraction, 544 Acetone, thenoyltrifluoro-liquid-liquid extraction, 544 Acetone, trifluorothenoyl-in analysis, 523 Acetonitrile electrochemistry in, 493 exchange reactions, 286 metal complexes hydrolysis, 428 Acetylacetone complexes, 22 liquid-liquid extraction, 543 Acetylacetone, hexafiuorothio-metal complexes gas chromatography, 560 Acetylactone, trifluorothio-metal complexes gas chromatography, 560 Acetylation metal complexes, 421 Acetylenedicarboxylic add dimethyl ester cycloaddition reactions, 458 Acid alizarin black SN metallochromic indicator, 556 Actinoids... 

In contrast to the previous chapters dealing with the deprotonation (metallation) of the substrate this chapter focuses on metal halogen exchange reactions towards the desired organolithium intermediates using BuLi. This type of reaction is of particular importance for the selective synthesis of certain substitution patterns (Rappoport Marek, 2004). 

Unfortunately, experimental studies on the working mode of ruthenium-catalyzed direct arylations with organic (pseudo)hahdes were thus far not available. However, a beneficial effect of NaOAc in the stoichiomehic syntheses of mthena-cycles under mild reaction conditions was previously reported [43], and suggested a cooperative deprotonation/metallation mechanism for the C—H bond activation step. In analogy, a transition-state model 93 could account for the high efficacy observed with (H A)SPO preligands [39,41,42] in mthenium-catalyzed direct arylation reactions (Scheme 9.32). 

As carboxylic acid additives increased the efficiency of palladium catalysts in direct arylations through a cooperative deprotonation/metallation mechanism (see Chapter 11) [45], their application to ruthenium catalysis was tested. Thus, it was found that a ruthenium complex modified with carboxylic acid MesC02H (96) displayed a broad scope and allowed for the efficient directed arylation of triazoles, pyridines, pyrazoles or oxazolines [44, 46). With respect to the electrophile, aryl bromides, chlorides and tosylates, including ortho-substituted derivatives, were found to be viable substrates. It should be noted here that these direct arylations could be performed at a lower reaction temperatures of 80 °C (Scheme 9.34). 

When an aromatic group is required in a crown ether, it is usually incorporated through the reaction of catechol because it gives an ideal coordination environment for a deprotonating metal to remain bonnd to the ligand. The same metal then forms a template that preorganizes the difunctionaUzed polyether, introdnced to form the remainder of the macrocycle, snch that it can react with the phenolic nncleophile. 

DEPROTONATIVE METALATION USING ALKALI METAL-NONALKALI METAL COMBINATIONS... 

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