Olefination of arenes is challenging because there are a number of positions on the aromatic ring to which the olefin can attach and there by leading to different isomers. One way is to follow the Heck reaction. The main criteria required for this reaction is that, the target carbon of the ring to be halogenated. And as synthetic chemists we know how tricky to get the halogenated compounds and that is why this reaction has limited applications. Its interesting to note that researchers from Scripps Research Institute have come with a novel procedure, where in there is no compulsion of halogenated compound.
As per the claim by the authors, the procedure is operationally simple, economical. The presence of a carboxyl group adjacent to the target C-H on the ring results in a phenomenon called the complex-induced proximity effect, which pulls the catalyst towards the relevant bond. In cases where the two ortho positions are equivalent, this approach alone can result in good yields of the desired product. When the substituents are different, the selectivity has been achieved by the use of amino acid-derived ligands between sterically and electronically similar ortho positions - which is really interesting...
http://www.rsc.org/chemistryworld/News/2009/November/27110902.asp
As per the claim by the authors, the procedure is operationally simple, economical. The presence of a carboxyl group adjacent to the target C-H on the ring results in a phenomenon called the complex-induced proximity effect, which pulls the catalyst towards the relevant bond. In cases where the two ortho positions are equivalent, this approach alone can result in good yields of the desired product. When the substituents are different, the selectivity has been achieved by the use of amino acid-derived ligands between sterically and electronically similar ortho positions - which is really interesting...
http://www.rsc.org/chemistryworld/News/2009/November/27110902.asp
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