The Meyer–Schuster Rearrangement

Abstract

The Meyer–Schuster rearrangement corresponds to a formal 1,3‐shift of a propargylic alcohol to afford the corresponding α,β‐unsaturated carbonyl compound via tautomerization of an allenol intermediate. The original acidic and harsh conditions have been replaced with mild and selective conditions that are compatible with a variety of functional and protecting groups. Commonly employed strategies include the activation of propargylic alcohols as esters, transition‐metal catalysis (e.g., gold complexes and oxometal complexes), and the C–H bond activation of terminal propargylic alcohols by transition‐metal insertion. The Meyer–Schuster rearrangement has been extended to all classes of propargylic alcohols and esters, including C sp ‐heteroatom‐substituted alkynols, as well as to propargylic amine derivatives (i.e., the aza‐Meyer–Schuster rearrangement). Moreover, the rearrangement can be employed in inter‐ and intramolecular one‐pot consecutive reactions, wherein multiple carbon–carbon and/or carbon–heteroatom bonds are formed. The Meyer–Schuster reaction exhibits a high atom economy, simple experimental procedures, and good‐to‐excellent product yields and stereoselectivities. Moreover, starting materials are easily accessible, and any toxic metals are employed in substoichiometric amounts. As such, the Meyer–Schuster rearrangement compares favorably with other standard protocols, such as the Wittig reaction, for the preparation of α,β‐unsaturated carbonyl compounds and derivatives. This review covers the literature since the identification of the reaction up to the end of 2020 and includes relevant references through November 2023. Both the mechanistic features and the regio‐ and stereoselectivity issues are discussed as they relate to the reaction conditions. The scope and limitations of the reaction are presented, as are a selection of synthetic applications, several general experimental procedures, and a comparison of the Meyer–Schuster rearrangement with other known methods. Finally, the tabular survey highlights the broad range of starting materials and products possible with the Meyer–Schuster rearrangement.