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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).
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:
The Chan–Lam coupling reaction, also known as the Chan–Evans–Lam coupling, is a cross-coupling reaction between an aryl boronic acid and an alcohol or an amine to form the corresponding secondary aryl amines or aryl ethers, respectively. [1] The Chan–Lam coupling is catalyzed by copper complexes. It can be conducted in air at room ...
Pd-BrettPhos complexes catalyze the coupling of weak nucleophiles with aryl halides. Such catalysts are selective for the monoarylation of primary amines. Other applications of BrettPhos in catalysis include trifluoromethylation of aryl chlorides, [45] the formation of aryl trifluoromethyl sulfides, [46] and Suzuki-Miyaura cross-couplings. [47]
Both palladium and copper complexes of the compound exhibit high activity for the coupling of aryl halides and aryl tosylates with various amides. [1] It is also an efficient ligand for several commonly used C–C bond-forming cross-coupling reactions, including the Negishi, Suzuki, and the copper-free Sonogashira coupling reactions.
Some of the cross-coupling reactions that include a transmetalation step are Stille cross-coupling, Suzuki cross-coupling, Sonogashira cross-coupling, and Negishi cross-coupling. The most useful cross-coupling catalysts tend to be ones that contain palladium. Cross-coupling reactions have the general form of R′–X + M–R → R′–R + M ...
In cross-coupling reactions, the component reagents are called cross-coupling partners or simply coupling partners. These reagents can be further classified according to their nucleophilic vs electrophilic character: R-X + R'-Y → R-R' + XY. Typically the electrophilic coupling partner (R-X) is an aryl halide, but triflates are also used ...
Although the Fukuyama cross-coupling reaction has been widely used in natural product synthesis, the reaction mechanism remains unclear.Various catalysts have been shown to promote reactivity, including Pd/C, Pd(OH) 2 /C, Pd(OAc) 2, PdCl 2, NiCl 2, Ni(acac) 2, etc. [2] The proposed catalytic cycle using Pd(OH) 2 /C (Pearlman’s catalyst) features the in situ generation of active Pd/C by ...