The Claisen and Cope Rearrangements

Since the first observation of a thermal rearrangement vinyl allyl ether to the corresponding homoallylcyclic carbonyl compound by Claisen in 1912, rearrangements of vinyl and aryl allylic ethers have been extensively studied and exploited for their synthetic value. The corresponding rearrangement of substituted 1,5-hexadiene was first recognized by Cope in 1940 as the carbon analog of the Claisen rearrangement. Today it is recognized that such transformations fall within the general category of a [3,3] sigamtropic reaction and that considerable variation may be accommodated in the basic requirement of a system of six atoms with terminal unsaturated linkage. This chapter attempts to survey the vas t accumulation of Claisen and Cope rearrangements recorded since the first coverage in 1944. Keywords: Claisen rearrangments; Cope rearrangements; allyl ethers; aliphatic rearrangements; anomalies; amine rearrangements; thio rearrangements; migration; experimental procedures