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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.
Successful reactions with aldehydes often require special solvents to be used, such as DMSO [4] or 1,2-dimethoxyethane with a trace amount of ethanol. [3] Additionally, LiOH fails to form the necessary adduct with alkynes to initiate the reaction.
The second step of the reaction to convert dibromoolefins to alkynes is known as Fritsch–Buttenberg–Wiechell rearrangement. 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
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 imine can isomerise and the alkyne group is placed at the other available nitrogen alpha position. [11] [12] [13] This reaction requires a copper catalyst. The redox A 3 coupling has the same product outcome but the reactants are again an aldehyde, an amine and an alkyne as in the regular A 3 coupling. [11] [14] [15] [16]
The hydroboration of alkynes gives vinylic boranes which oxidize to the corresponding aldehyde or ketone. In the thiol-yne reaction the substrate is a thiol. Addition of hydrogen halides has long been of interest.
Multiple carbon–carbon bond are replaced by carbonyl (C=O) groups, such as aldehydes, ketones, and carboxylic acids. The reaction is predominantly applied to alkenes, but alkynes and azo compounds are also susceptible to cleavage. The outcome of the reaction depends on the type of multiple bond being oxidized and the work-up conditions. [1]
Once a terminal alkyne is achieved, the 3-aminopropylamine anion will attack and remove the terminal proton. However, the process stops there because the carbon-hydrogen bond electrons cannot form an additional pi-bond on top of the alkyne. [3] [1] Therefore, an acetylide anion is produced. A mild acid workup will quench the acetylide anion and ...