Claisen Rearrangement
The Claisen rearrangement is a pericyclic reaction (concerted reaction + cyclic transition state) that belongs to the group of sigmatropic reactions (one σ-bond is exchanged to another). A [3,3] sigmatropic rearrangement where an allyl vinyl ether is converted to an unsaturated carbonyl compound.
General features:
1. The reaction can be also described as a suprafacial, concerted, nonsynchronous [3,3]-sigmatropic rearrangement. 2. If chiral allylic alcohols are used to prepare the starting allyl vinyl ether, then the chirality is transferred to the products.
Claisen Rearrangement
Reaction Mechanism
Experimental Procedure
A solution of the allyl vinyl ether (30.5 mmol) in DMF (250 mL) was heated at 140–150 °C for 18 h. Upon completion, the reaction mixture was cooled to room temperature, diluted with Et2O, and washed with saturated aqueous sodium bicarbonate and water. The combined aqueous layers were further extracted with Et2O. The combined organic layers were dried (Na2SO4), filtered, and concentrated. The residue was purified by column chromatography to give the desired product.
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