To use all functions of this page, please activate cookies in your browser.
With an accout for my.chemeurope.com you can always see everything at a glance – and you can configure your own website and individual newsletter.
- My watch list
- My saved searches
- My saved topics
- My newsletter
In organic chemistry, an electrocyclic reaction is a type of pericyclic rearrangement reaction where the net result is one pi bond being converted into one sigma bond. These reactions are usually unnamed, being categorized by the following criteria:
Additional recommended knowledge
The torquoselectivity in an electrocyclic reaction is the measure of selectivity in the direction of the conrotatory or disrotatory mode.
For example in scheme 1 a [6-pi] electrocyclic ring closure takes all-cis hexatriene to 1,4-cyclohexadiene.
An often studied electrocyclic reaction is the conrotatory thermal ring-opening of benzocyclobutane. The reaction product is a very unstable ortho-quinodimethane but this molecule can be trapped in an endo addition with a strong dienophile such as maleic anhydride to the Diels-Alder adduct. The chemical yield for the ring opening of the benzocyclobutane depicted in scheme 2 is found to depend on the nature of the substituent R . With a reaction solvent such as toluene and a reaction temperature of 110°C, the yield increases going from methyl to isobutylmethyl to trimethylsilylmethyl. The increased reaction rate for the trimethylsilyl compound can be explained by silicon hyperconjugation as the βC-Si bond weakens the cyclobutane C-C bond by donating electrons.
The Nazarov cyclization reaction is a named electrocyclic reaction converting divinylketones to cyclopentenones.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Electrocyclic_reaction". A list of authors is available in Wikipedia.|