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Alkyne metathesis is an organic reaction that entails the redistribution of alkyne chemical bonds. The reaction requires metal catalysts. The reaction requires metal catalysts. Mechanistic studies show that the conversion proceeds via the intermediacy of metal alkylidyne complexes .
The conversion provides a useful approach for remote functionalization in long-chain alkynes. [2] The reaction requires a strong base. The base used by Brown and Yamashita was potassium 1,3-diaminopropanide, generated in situ by adding potassium hydride to the solvent 1,3-diaminopropane. [1]
In organic chemistry, the Doering–LaFlamme allene synthesis is a reaction of alkenes that converts them to allenes by insertion of a carbon atom. [1] This name reaction is named for William von Eggers Doering and a co-worker, who first reported it.
An enyne metathesis is an organic reaction taking place between an alkyne and an alkene with a metal carbene catalyst forming a butadiene. This reaction is a variation of olefin metathesis. [1] The general scheme is given by scheme 1: When the reaction is intramolecular (in an enyne) it is called ring-closing enyne metathesis or RCEYM (scheme 2):
This first part of the process is a so-called A 3 coupling reaction (A 3 stands for aldehyde-alkyne-amine). In the second part, the α-amino alkyne then undergoes a formal retro-imino-ene reaction, an internal redox process, to deliver the desired allene and an imine as the oxidized byproduct of the secondary amine. [11]
The overall combined transformation of an aldehyde to an alkyne by this method is named after its developers, American chemists Elias James Corey and Philip L. Fuchs. The Corey–Fuchs reaction. By suitable choice of base, it is often possible to stop the reaction at the 1-bromoalkyne, a useful functional group for further transformation.
The metal-mediated processes include a carbonyl-olefination and an olefin–olefin metathesis event. There are two general mechanistic schemes to perform this overall transformation: one, reaction of a [M=CHR 1] reagent with an alkene to generate a new metal alkylidene, which then couples with a carbonyl group to form the desired substituted alkene and an inactive [M=O] species (type A); two ...
In organic chemistry, alkynylation is an addition reaction in which a terminal alkyne (−C≡CH) is added to a carbonyl group (C=O) to form an α-alkynyl alcohol (R 2 C(−OH)−C≡C−R). [1] [2] When the acetylide is formed from acetylene (HC≡CH), the reaction gives an α-ethynyl alcohol. This process is often referred to as ethynylation.