To use all functions of this page, please activate cookies in your browser.
my.chemeurope.com
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
Carroll rearrangementThe Carroll rearrangement is a rearrangement reaction in organic chemistry and involves the transformation of a β-keto allyl ester into a α-allyl-β-ketocarboxylic acid.[1] This organic reaction is accompanied by decarboxylation and the final product is a γ,δ-allylketone. The Carrol rearrangement is an adaptation of the Claisen rearrangement and effectively a decarboxylative Allylation. Additional recommended knowledgeReaction mechanismThe Carrol rearrangement (1940) in the presence of base and with high reaction temperature (path A) takes place through an intermediate enol which then rearranges in an electrocyclic Claisen rearrangement. The follow up is a decarboxylation. With palladium(0) as a catalyst, the reaction (Tsuji, 1980) is much milder (path B) with an intermediate allyl cation / carboxylic acid anion organometallic complex [2].
Asymmetric decarboxylative allylationBy introducing suitable chiral ligands, the reaction becomes enantioselective [4]. The first reported asymmetric rearrangement is catalyzed by tris(dibenzylideneacetone)dipalladium(0) and the Trost ligand [3]: A similar reaction [5] uses additional naphthol. This reaction delivers one enantiomer with 88% ee. It remains to be seen if this reaction will have a wide scope because the acetamido group appears to be a prerequisite. The same catalyst but a different ligand is employed in this enantioconvergent reaction [6]: The scope is extended to asymmetric α-alkylation of ketones masked as their enol carbonate esters [7]: References
Categories: Rearrangement reactions | Palladium |
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Carroll_rearrangement". A list of authors is available in Wikipedia. |