TheClaisen andCope Rearrangements

Abstract

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.

A continuous-flow resonator-type microwave reactor for high-efficiency organic synthesis and Claisen rearrangement as a model reaction

“…Traces of unreacted 1 (1.3%), in addition to the o-Claisen rearrangement product 2-allyl-1-naphthol (2) (86.3%) and a small amount of p-Claisen rearrangement product 4-allyl-1-naphthol (3) (3.3%) were observed in the reaction mixture. In Claisen rearrangements of allyl aryl ethers, the o-Claisen rearrangement product often undergoes enolization to give an o-allyl phenol derivative [65,66]. Moreover, it is known that the p-Claisen rearrangement product occurs for allyl aryl ethers with substitution at the o-position via Cope rearrangement of the enol intermediate [67].…”

Synthesis and SAR of Lehualide B: A Marine-Derived Natural Product with Potent Anti-Multiple Myeloma Activity

“…Well-established Claisen rearrangement chemistry 33, 34 was envisioned as a means to convert allylic alcohol 12 to an ( E )-trisubstituted alkene (as in 11 ), while Ti-mediated, alkoxide-directed reductive cross-coupling could then be employed to convert allylic alcohol 11 to the desired ( Z )-trisubstituted C12-C13 alkene of lehualide B. In this latter process, stereochemical control was predicted in accord with our previous studies that put forth an empirical model based on a boat-like transition state geometry for carbometalation that features minimization of A1,2-strain (Figure 2C; A → B → C ).…”

A Half‐Century Odyssey in the Realm of Reactive Intermediates

“…Chapter 11, by Sara Jane Rhoads, described "no mechanism reactions," a "term originated by Prof. W. von E. Doering as a humorous way of calling attention to the serious predicament organic chemists are in when the classical criteria of mechanism arent fulfilled." [47] The reactions in question were, for example, the Cope and Claisen rearrangements and the Diels-Alder reaction-that is, reactions in which the standard ionic or radical intermediates did not come into play. It took the revolution initiated by the WoodwardÀHoffmann rules to provide theoretical insight into the mechanisms and transition states of these reactions.…”