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The Heck reaction (also called the Mizoroki–Heck reaction) [1] is the chemical reaction of an unsaturated halide (or triflate) with an alkene in the presence of a base and a palladium catalyst to form a substituted alkene. It is named after Tsutomu Mizoroki and Richard F. Heck.
The Heck reaction is the palladium-catalyzed coupling of an aryl or alkenyl halide with an alkene to form a substituted alkene. [2] Intramolecular variants of the reaction may be used to generate cyclic products containing endo or exo double bonds. Ring sizes produced by the intramolecular Heck reaction range from four to twenty-seven atoms.
The proposed Heck catalytic cycle involving cationic palladium with diazonium salts was reinforced by studies with mass spectrometry (ESI) by Correia and co-workers. [1] These results also show the complex interactions that occur in the coordination sphere of palladium during the Heck reaction with arenediazonium salt. HM Mechanism
The most common type of coupling reaction is the cross coupling reaction. [1] [2] [3] Richard F. Heck, Ei-ichi Negishi, and Akira Suzuki were awarded the 2010 Nobel Prize in Chemistry for developing palladium-catalyzed cross coupling reactions. [4] [5] Broadly speaking, two types of coupling reactions are recognized:
Many mechanisms exist reflecting the myriad types of cross-couplings, including those that do not require metal catalysts. [7] Often, however, cross-coupling refers to a metal-catalyzed reaction of a nucleophilic partner with an electrophilic partner. Mechanism proposed for Kumada coupling (L = Ligand, Ar = Aryl).
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Plucinkski and coworkers developed a continuous Mizoroki-Heck and hydrogenation sequence consisting of two separated packed-bed reactors containing Pd/C. [15] Because the Pd/C-catalyzed hydrogenation proceeds via a heterogeneous mechanism, [16] metal leaching due to the second hydrogenation step is minimal, and Pd leached from the first part of ...