Search results
Results from the WOW.Com Content Network
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:
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]
The Hiyama coupling is a palladium-catalyzed cross-coupling reaction of organosilanes with organic halides used in organic chemistry to form carbon–carbon bonds (C-C bonds). This reaction was discovered in 1988 by Tamejiro Hiyama and Yasuo Hatanaka as a method to form carbon-carbon bonds synthetically with chemo - and regioselectivity . [ 1 ]
The first example of organogermanes used in transition-metal-catalyzed cross-coupling reaction was reported in 2004. [1] However, due to the toxicity, low reactivity (compared with other Ar–[M] nucleophiles) and poor stability of ArGeCl 3, this reaction was demonstrated not to be synthetically applicable.
Heterogeneous metal catalyzed cross-coupling is a subset of metal catalyzed cross-coupling in which a heterogeneous metal catalyst is employed. Generally heterogeneous cross-coupling catalysts consist of a metal dispersed on an inorganic surface or bound to a polymeric support with ligands .
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 ...
The Sonogashira cross-coupling reaction has been employed in a wide variety of areas, due to its usefulness in the formation of carbon–carbon bonds. The reaction can be carried out under mild conditions, such as at room temperature, in aqueous media, and with a mild base, which has allowed for the use of the Sonogashira cross-coupling ...