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The Claisen rearrangement (not to be confused with the Claisen condensation) is a powerful carbon–carbon bond-forming chemical reaction discovered by Rainer Ludwig Claisen. The heating of an allyl vinyl ether will initiate a ()-sigmatropic rearrangement to give a γ,δ-unsaturated carbonyl. Discovered in 1912, the Claisen rearrangement is the first recorded example of a ()-sigmatropic rearrangement. Many reviews have been written.〔Hiersemann, M.; Nubbemeyer, U. (2007) ''The Claisen Rearrangement''. Wiley-VCH. ISBN 3-527-30825-3〕 ==Mechanism== The Claisen rearrangement is an exothermic (about 84 kJ mol−1), concerted pericyclic reaction which according to the Woodward–Hoffmann rules shows a suprafacial reaction pathway. Crossover experiments eliminate the possibility of the rearrangement occurring via an intermolecular reaction mechanism and are consistent with an intramolecular process, now understood as a ()-electrocyclic reaction. There are substantial solvent effects in the Claisen reactions. More polar solvents tend to accelerate the reaction to a greater extent. Hydrogen-bonding solvents gave the highest rate constants. For example, ethanol/water solvent mixtures give rate constants 10-fold higher than sulfolane.〔〔 Trivalent organoaluminium reagents, such as trimethylaluminium, have been shown to accelerate this reaction. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Claisen rearrangement」の詳細全文を読む スポンサード リンク
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