What is coupling reaction in organic chemistry

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Palladium-Catalyzed Linkage Reactions - Introduction

One of the most important areas of organic chemistry is synthetic chemistry. Chemists working in this field often face the challenge of synthesizing complex compounds from smaller molecules. In order to do this, reactions are needed that allow the creation of new bonds. The most important reactions include those that serve to link carbon atoms. A large number of reactions in many variants are now available for this purpose. Particularly well-suited, established reactions are often closely linked to the names of their discoverers as so-called name reactions, e.g. B. the Grignard reaction, the Diels-Alder cyclization or the Wittig olefination - three reactions that are so important that their discoverers were awarded the Nobel Prize in Chemistry.

However, since not every reaction can be applied to every problem, new reactions and reaction variants are constantly being developed. The newer methods also include the palladium-catalyzed linkage reactions, such as. B. the so-called cross-coupling or the Heck reaction. These reactions have become so important in synthetic organic chemistry that Richard F. Heck, Ei-ichi Negishi and Akira Suzuki were awarded the Nobel Prize for Chemistry 2010 for their work in this area (link to the official Nobel Prize page).

Palladium-catalyzed cross-coupling

Cross-couplings are among the most prominent palladium-catalyzed reactions. The different variants can be simplified to the general reaction scheme shown below (Fig. 1). In cross-coupling, for example, an electrophilic substrate reacts with a nucleophilic reaction partner in the presence of a palladium catalyst to form a new bond to form a molecule. Common radicals are aryl, alkenyl, alkynyl and benzyl, in some cases also alkyl or acyl, is usually aryl, alkenyl, alkynyl or alkyl. Bromine, iodine or triflate (trifluoromethanesulphonate) are often used as a group. The group denotes a - mostly organometallic - residue, e.g. B. zinc, tin, magnesium but also boron organyls.