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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 coupling of 2-chlorobenzoic acid and aniline is illustrative: [4] C 6 H 5 NH 2 + ClC 6 H 4 CO 2 H + KOH → C 6 H 5 N(H)−C 6 H 4 CO 2 H + KCl + H 2 O. A typical catalyst is formed from copper(I) iodide and phenanthroline. The reaction is an alternative to the Buchwald–Hartwig amination reaction.
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.
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
The Negishi coupling is a widely employed transition metal catalyzed cross-coupling reaction. The reaction couples organic halides or triflates with organozinc compounds, forming carbon-carbon bonds (C-C) in the process. A palladium (0) species is generally utilized as the catalyst, though nickel is sometimes used.
Decarboxylative cross coupling reactions are chemical reactions in which a carboxylic acid is reacted with an organic halide to form a new carbon-carbon bond, concomitant with loss of CO 2. Aryl and alkyl halides participate. Metal catalyst, base, and oxidant are required. Decarboxylative cross-coupling general reaction scheme
In organic chemistry, phosphonium coupling is a cross-coupling reaction for organic synthesis. It is a mild, efficient, chemoselective and versatile methodology for the formation of C–C, C–N, C–O, and C–S bond of unactivated and unprotected tautomerizable heterocycles. The method was originally reported in 2004. [1]