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All feature three contiguous sp²-hybridized carbon centers and all derive stability from resonance. [6] Each species can be presented by two resonance structures with the charge or unpaired electron distributed at both 1,3 positions. Resonance structure of the allyl anion. The cation is identical, but carries an opposite-sign charge. [7]
The scope of the Corey-House synthesis is exceptionally broad, and a range of lithium diorganylcuprates (R 2 CuLi, R = 1°, 2°, or 3° alkyl, aryl, or alkenyl) and organyl (pseudo)halides (RX, R = methyl, benzylic, allylic, 1°, or cyclic 2° alkyl, aryl, or alkenyl and X = Br, I, OTs, or OTf; X = Cl is marginal) will undergo coupling as the nucleophilic and electrophilic coupling partners ...
Lithium–halogen exchange is frequently used to prepare vinyl-, aryl- and primary alkyllithium reagents. Vinyl halides usually undergo lithium–halogen exchange with retention of the stereochemistry of the double bond. [2] The presence of alkoxyl or related chelating groups accelerates lithium–halogen exchange. [3]
The Hiyama coupling can be applied to the formation of C sp 2-C sp 2 (e.g. aryl–aryl) bonds as well as C sp 2-C sp 3 (e.g. aryl–alkyl) bonds. Good synthetic yields are obtained with couplings of aryl halides, vinyl halides, and allylic halides and organoiodides afford the best yields.
Vinyl, aryl and tertiary alkyl halides are unreactive; as a result, the reaction of NaI in acetone can be used as a qualitative test to determine which of the aforementioned classes an unknown alkyl halide belongs to, with the exception of alkyl iodides, as they yield the same product upon substitution.
β-Carbon elimination (beta-carbon elimination) is a type of reaction in organometallic chemistry wherein an allyl ligand bonded to a metal center is broken into the corresponding metal-bonded alkyl (aryl) ligand and an alkene. [1] It is a subgroup of elimination reactions.
β-Hydride elimination is a reaction in which a metal-alkyl centre is converted into the corresponding metal-hydride-alkene. [1] β-Hydride elimination can also occur for many alkoxide complexes as well. The main requirements are that the alkyl group possess a C-H bond β to the metal and that the metal be coordinatively unsaturated.
Boronic acids and esters are classified depending on the type of carbon group (R) directly bonded to boron, for example alkyl-, alkenyl-, alkynyl-, and aryl-boronic esters. The most common type of starting materials that incorporate boronic esters into organic compounds for transition metal catalyzed borylation reactions have the general ...