Sonogashira reaction compounds

Extended tetrathiafulvalenes with acetylenic cores are interesting compounds because of their redox and chromophoric properties. Such molecules are both interesting from materials and supramolecular chemistry perspectives. A tetraethynylethene-extended tetrathiafulvalene, for instance, was prepared using a microwave-promoted Sonogashira reaction [72]. Coup-... 

The chemical structure of the polymers was confirmed by NMR and elemental analysis, and spectroscopically characterized in comparison with monodisperse low molecular weight model compounds. Scheme 5 outlines the approach to the model compounds. Model compounds 31-34 were synthesized by complexation of the ruthenium-free model ligands 29/30 with 3/4. The model ligands were synthesized in toluene/diisopropylamine, in a similar fashion as the polycondensation using Pd(PPh3)4 and Cul as catalyst (Sonogashira reaction) [34,47-49]. 

The Sonogashira reaction is a C-C coupling reaction of terminal alkynes with aryl or vinyl halides in presence of Pd(0) metal and/or Cu(i) catalyst. These compounds are useful in synthesizing species having pharmaceutical... 

Corma et al compared the use of different IL solvents and polyethylene glycol (PEG) using a carbopalladacycle complex as catalyst for Suzuki and Sonogashira reactions. They showed that the dialkyl-substituted imidazolium compounds had poor stability, reactivity and recyclability when compared with trialkyl substituted imidazolium compounds and PEG. They concluded that this result could be attributed to the stabilization of the Pd nanoparticles in the solvent. They showed that PEG was a better solvent since it gave better yields, had good stability, low cost and low toxicity. 

The Sonogashira reaction is used a lot because of the great potential of ene-diyne antibiotics. Symmetrical ene-diynes may be synthesized in one step from two molecules of a terminal alkyne and Z-dihaloethene. The ene-diyne part of the molecule does the remarkable Bergmann cyclization to give a benzene diradical the ene-diyne is able to penetrate DNAand the diradical is able to react with it. These compounds are anticancer drugs of some promise. 

The moisture stability of the organostannanes and good functional group tolerance of the reaction make it most extensively used in coupling reactions. However, toxicity and low polarity of tin compounds are certain drawbacks of the use of the Stille reaction. The Suzuki coupling makes use of boronic acids and their derivatives, which is an improvement on the Stille coupling. In contrast to the Suzuki, Kumada, Heck and Sonogashira reactions which are carried out under basic conditions, the Stille reaction can be carried out under neutral conditions. 

An elegant method for linking terminal alkynes with aromatic compounds and olefins is the Sonogashira reaction [15]. The palladium-catalyzed reaction enables the simultaneous introduction of two or even more alkyne units and thereby makes it possible to synthesize acetylene derivatives, for example hexaalkynyl-benzenes [16], (eq. (7)), which can be obtained only with difficulty by other methods. It has been shown by Herrmann, Beller, and co-workers that the copper reagent is not necessary as a co-catalyst for the coupling of terminal alkynes with sp -carbon halides. By using phosphapalladacyclic catalysts 1 the... 

The synthesis of derivatized, concave pyridines could be accomplished in a straightforward manner [118]. Thus, 335 could be transformed to 336 upon cross-coupling with phenylacetylene. Furthermore, the Sonogashira reaction was also able to generate dimerized variations 338 of these compounds by reacting 337 with 325. 

In a reaction which demonstrates the functional group tolerance of the Sonogashira reaction, Cristalli and coworkers synthesized 143 as one of the number of derivatives of adenosine-5 -V-ethyluronamide [77]. This, along with several other derivatives was screened to assess potency in binding at the A2a over the Aj adenosine receptor. Compound 143 was found to be virtually non-selective for the A2a receptor (2.1 1), but possessed substantial vasodilating activity. 

In recent years, several natural products containing 2,4-disubstituted oxazoles have been isolated and their synthetic routes were investigated. Several key intermediates required for the synthesis of target compounds were achieved via the Stille, Suzuki, Heck, and Sonogashira reactions. In addition, several 2,5-diaryloxzoles were prepared from 2-halo-... 

Schreiber s early efforts in this area were focused on libraries of compounds having structural features reminiscent of rigid, complex, stereochemically rich natural products. In a key early example, solid-phase split-pool synthesis was used to generate a combinatorial library of over two million complex, polycyclic compounds derived from shikimic acid [17]. A stereoselective tandem acylation-nitrone cycloaddition was used to generate 18 tetracyclic scaffolds, to which 30 alkynes were coupled using a Sonogashira reaction, 62 amines were coupled via y -lactone aminolysis, and 62 carboxylic acids were coupled by alcohol esterification (Fig. 9.1-3(c)). In addition, a portion of the solid supports were left unreacted at each of the last three steps to generate a skip codon that further increased the diversity of the library. 

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