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In organic chemistry, a cross-coupling reaction is a reaction where two different fragments are joined. Cross-couplings are a subset of the more general coupling reactions. Often cross-coupling reactions require metal catalysts. One important reaction type is this:
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 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.
The major drawback of the Negishi coupling, aside from its water and oxygen sensitivity, is its relative lack of functional group tolerance when compared to other cross-coupling reactions. [39] (−)-stemoamide is a natural product found in the root extracts of ‘’Stemona tuberosa’’.
Pd-catalyzed decarboxylative cross-coupling of aryl halides with potassium cyanoacetate, reported by Yeung et al. Contrarily to Cu-only systems, decarboxylative palladation is the rate-limiting step in the palladium catalytic cycle. [4] Decarboxylative cross-coupling of potassium polyfluorobenzoates, reported by Shang et al.
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 ...
This reaction is notable for using organolithiums as opposed to other cross-coupling reactions which utilize various metal-carbon compounds (metal = tin, magnesium, boron, silicon, zinc). Since the production of these other coupling reagents relies heavily upon organolithiums (especially in the case of organozinc and organomagnesium compounds ...
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 ]