Claisen Rearrangement

Claisen rearrangement is one of [3,3]-sigmatropic rearrangements which provides γ,δ-unsaturated carbonyl compounds from ally vinyl ethers and allyl phenols. The reaction is considered to proceed via chair-like transition state and has an advantage that it is expected from substrate’s stereochemistry. Modified Claisen rearrangement reactions such as aza-Claisen, Johnson-Claisen, Eschenmoser-Claisen and Ireland-Claisen rearrangement are used according to the choice and property of substrates and products.