Claisen rearrangement

== English == === Etymology === Discovered by German chemist Rainer Ludwig Claisen. === Noun === Claisen rearrangement (plural Claisen rearrangements) (organic chemistry) A powerful carbon–carbon bond-forming chemical reaction, in which the heating of an allyl vinyl ether initiates a [3,3]-sigmatropic rearrangement to give a γ,δ-unsaturated carbonyl.