Search results
Results From The WOW.Com Content Network
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
To illustrate the impact of suboptimal coupling yields for a given synthesis, consider the case where each coupling step were to have at least 99% yield: this would result in a 77% overall crude yield for a 26-amino acid peptide (assuming 100% yield in each deprotection); if each coupling were 95% efficient, the overall yield would be 25%.
Amide coupling is one of the most common reactions in organic chemistry and DMTMM is one reagent used for that reaction. The mechanism of DMTMM coupling is similar to other common amide coupling reactions involving activated carboxylic acids. [1] Its precursor, 2-chloro-4,6,-dimethoxy-1,3,5-triazine (CDMT), has also been used for amide coupling.
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 reaction mechanism for this reaction has been demonstrated to proceed through steps similar to those known for palladium catalyzed CC coupling reactions. Steps include oxidative addition of the aryl halide to a Pd(0) species, addition of the amine to the oxidative addition complex, deprotonation followed by reductive elimination .
Although the Fukuyama cross-coupling reaction has been widely used in natural product synthesis, the reaction mechanism remains unclear.Various catalysts have been shown to promote reactivity, including Pd/C, Pd(OH) 2 /C, Pd(OAc) 2, PdCl 2, NiCl 2, Ni(acac) 2, etc. [2] The proposed catalytic cycle using Pd(OH) 2 /C (Pearlman’s catalyst) features the in situ generation of active Pd/C by ...