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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:
CCL2 may represent a molecular link in the negative cross-talk between adipose tissue and skeletal muscle assigning a completely novel important role to CCL2 besides inflammation. [ 31 ] Incubation of HL-1 cardiomyocytes and human myocytes with oxidized-LDL induced the expression of BNP and CCL2 genes, while native LDL (N-LDL) had no effect.
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 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.
Many decarboxylative cross coupling reactions involve the breaking of sp 2 C–COOH and sp C–COOH bonds, therefore subsequent studies have attempted to enable cross coupling with sp 3 C carboxylic acids. One such reaction by Shang et al. described a palladium catalyzed cross coupling that enables the formation of functionalized pyridines ...
A typical example of classic Ullmann biaryl coupling is the conversion of ortho-chloronitrobenzene into 2,2'-dinitrobiphenyl with a copper - bronze alloy. [9] [10] 2 C 6 H 4 (NO 2)Cl + 2 Cu → (C 6 H 4 (NO 2)) 2 + 2 CuCl. The reaction has been applied to fairly elaborate substrates. Ullmann reaction
In chemistry and biology, a cross-link is a bond or a short sequence of bonds that links one polymer chain to another. These links may take the form of covalent bonds or ionic bonds and the polymers can be either synthetic polymers or natural polymers (such as proteins ).
The first example of a palladium catalyzed C–N cross-coupling reaction was published in 1983 by Migita and coworkers and described a reaction between several aryl bromides and N,N-diethylamino-tributyltin using 1 mol% PdCl 2 [P(o-tolyl) 3] 2.