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Fmoc-Oxyma-Synthese. or the coupling reagent COMU which is readily soluble as a dimethylmorpholine-uronium salt and which, like Oxyma, is superior to the standard additive HOBt for the suppression of racemization and acylation efficiency and is comparable to HOAt without presenting an explosion risk such as the benzotriazoles. [5]
In one important reaction type, a main group organometallic compound of the type R-M (where R = organic group, M = main group centre metal atom) reacts with an organic halide of the type R'-X with formation of a new carbon-carbon bond in the product R-R'. The most common type of coupling reaction is the cross coupling reaction. [1] [2] [3]
The Seyferth–Gilbert homologation is a chemical reaction of an aryl ketone 1 (or aldehyde) with dimethyl (diazomethyl)phosphonate 2 and potassium tert-butoxide to give substituted alkynes 3. [1] [2] Dimethyl (diazomethyl)phosphonate 2 is often called the Seyferth–Gilbert reagent. [3] The Seyferth–Gilbert homologation
Cross-couplings are a subset of the more general coupling reactions. Often cross-coupling reactions require metal catalysts. One important reaction type is this: R−M + R'−X → R−R' + MX (R, R' = organic fragments, usually aryl; M = main group center such as Li or MgX; X = halide) These reactions are used to form carbon–carbon bonds but ...
These reagents attack the O-acylisourea intermediate to form an active ester, which subsequently reacts with the peptide to form the desired peptide bond. [15] Ethyl cyanohydroxyiminoacetate (Oxyma), an additive for carbodiimide coupling, acts as an alternative to HOAt. [16]
The McMurry reaction of benzophenone. The McMurry reaction is an organic reaction in which two ketone or aldehyde groups are coupled to form an alkene using a titanium chloride compound such as titanium(III) chloride and a reducing agent.
The Hiyama–Denmark coupling is the modification of the Hiyama coupling that does not require a fluoride additive to utilize organosilanols and organic halides as coupling partners. The general reaction scheme is shown below, showcasing the utilization of a Brønsted base as the activating agent as opposed to fluoride, phosphine ligands are ...
Oxidative coupling in chemistry is a coupling reaction of two molecular entities through an oxidative process.Usually oxidative couplings are catalysed by a transition metal complex like in classical cross-coupling reactions, although the underlying mechanism is different due to the oxidation process that requires an external (or internal) oxidant.