Bonding coupling reactions

The discoveries made possible by the use of 13C labels are outlined below. A new ene-imine carbon-carbon bond coupling reaction was discovered that afforded... 

Reetz and Sommer then studied the intramolecular hydroarylation of alkynes when they were looking for carbon triple bond coupling reactions. Depending on the substrate, the choice of gold(I) or gold(III) species was crucial [127]. 

One of the oldest ruthenium-catalyzed C=C bond coupling reactions deals with the selective dimerization of functionalized alkenes, especially the dimerization of acrylates [ 1,2]. It usually involves either an initial hydrometallation process, oxidative coupling, or vinyl C-H bond activation (Scheme 1). 

In reactions of alkenyl triflates with stereogenic C=C double bonds, coupling reactions of these kinds convert the Csp2—X bond of the alkenyl triflate into the Csp2—C bond of the substitution product with complete retention of configuration. The stereoselective synthesis of a 1,3-diene from an alkenyl triflate and (vinyl)2CuLi provides an example (Figure 13.1). 

Copper-promoted C-heteroatom bond-coupling reactions of N-H, O-H, and S-H containing substrates with aryl-boronic acids were found to proceed at room temperature in the presence of Cu(OAc)2 and an amine base.996-998 The reactions have been reviewed.3,999... 

BINAP also proved useful in the C-N bond coupling reactions involving halopyridines [128]. For example, the coupling of primary amines with chloro-and bromopyridines could be performed with the ( )-BINAP/Pd-catalyst in good yield, Eq. (157). 

An important class of carbon-carbon bond coupling reactions is the Diels-Alder reactions. An example of a Diels-Alder reaction is shown below ... 

An alternative approach may also consist of the de novo synthesis of the two carbohydrate substructures that would have to be grown from the termini of much simpler precursors. For classical chemical syntheses, tremendous difficulties are immediately obvious by the simultaneous needs of high relative stereocontrol and terminus differentiation for each individual step. A somewhat better perspective may be seen for the use of stereoselective biocatalysts for asymmetric C-C bond coupling reactions. Indeed, more than 30 aldolases are known from which recently a larger number has been studied extensively for their utility in asymmetric synthesis [30,37,38,41,42]. 

On the other hand, in the case of a chain reaction, an induced active bond continues to react until it loses its activity through the active bond coupling reaction 4 ). In this case, Charlesby showed that an active bond makes j/(l-j) crosslinking units, where j is termed the chain reaction activity ( i=l-j, where i is termed the inhibition activity by Charlesby ) and it depends on the individual monomer concentration 5 ). Thus, the relationship is expressed as... 

Some other C—C bond coupling reactions in micellar systems should be mentioned here. Monflier et al. [72] described, in both papers and patents, the telome-rization of 1,3-butadiene into octadienol in a micellar system by means of a palladium-phosphine catalyst. Water-soluble and amphiphilic phosphines have been used and the surfactants were widely varied. The authors have shown that the promoting effect of surfactants appeared above the CMCs of the surfactants, and they conclude that micellar aggregates were present in the reaction mixture. Cationic, anionic, and nonionic surfactants gave this micellar effect but the combination of the highly water-soluble TPPTS and the surfactant dodecyldimethylamine hydrocarbonate was found to be best. A speculation about the location of reactants shows that the reaction probably occurs in the interface between the micellar pseudophase and water. 

Carbon-carbon bond coupling reactions that link alkynyl ligands are potentially important reactions for the preparation of alkyne oligomers (372) and nonlinear optical materials, as well as carbocyclic and heterocyclic compounds (373, 374). As a metal-mediated strategy to these... 

To facilitate the use of these methods, the Tomkinson group has also developed three different Mrays to synthesize the JV-arylhydroxylamine precursors. The first two methods employ transition metal-mediated C—N bond coupling reactions which tolerate carbamate-protected N-functionalities and alkoxy or silyloxy 0-protecting groups tScheme 14.12eT ... 

Some drawbacks of the precursor routes mentioned above have been overcome by the use of polycondensation- and C-C-bond-coupling reactions. To produce soluble PPV-, poly(thiophene)-, or poly(pyrrol) derivatives for spin coating preparation, various types of transition metal catalyzed reactions, such as the Heck-, Suzuki-, and Sonogashira-reaction, Wittig- and Wittig-Horner-type coupling reactions, or the McMurry- and Knoevenagel-condensation have been utilized. 

Reductive C-C and N-N bond coupling reactions have also been reported for magnesium(l) compounds. Reactions of note here are those with the isocyanate, t-BuNCO, or 1-adamantyl azide (AdNa), which selectively afforded the magnesium oxamide compounds, 24 and 25, and the unusual hexazenediide complexes, 26 (Scheme 4) [28, 110]. Only one reduction of an unsaturated substrate has been reported that does not yield a dinuclear complex, i.e. the reduction of benzophenone with 3. This gave rise to a high yield of the thermally stable, purple-blue magnesium ketyl complex, 27, after addition of DM AP to the reaction mixture [111, 114]. 

The formed henzyl bromides can then potentially be used in a range of telescoped chemical transformations, including alkylations. The flow synthesis of a number of receptor ligands, using ben l bromides, has been demonstrated by Ulven. Alternatively, C-C bond coupling reactions can be performed using flow electrosynthesis, as shown in Scheme 12.6. ... 

The nickel complex displays a strong coordination of silylene chelate ligand to the nickel center. The COD and TMS groups at the nickel and bridging phosphorus atom provide sufficient steric stability to the complex. The nickel complex can be promising toward transition metal catalysis toward C—C bond coupling reactions. 

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