The document discusses the Claisen rearrangement reaction and its variations. It begins by describing the classical Claisen rearrangement of allyl vinyl ethers and its mechanism. It then discusses three variations: the Ireland–Claisen rearrangement of allylic carboxylates, the Johnson-Claisen rearrangement of allylic alcohols with orthoesters, and the Eschenmoser–Claisen rearrangement of allylic/benzylic alcohols with N,N-dimethylacetamide dimethyl acetal. It concludes by providing two examples of applications for Claisen rearrangements in synthesis: of o-eugenol and prephenate.