Umpolung of Enamines: An Overview on Strategies and Synthons

Abstract

Umpolung strategies are of considerable interest to organic chemists because they provide alternative synthetic routes to those imposed by the natural polarity of classical synthons. Reverse-polarity reactions of aldehydes, α,β-unsaturated carbonyl compounds, and imines are deeply embedded in the methodology of organic synthesis. In recent years, umpolung of enols and enamines has received much attention as a novel strategy to access α-substituted ketones. Here, state-of-the-art approaches to umpolung of enamine reactivity are discussed, with a particular focus on recent developments in this field from the author’s research group.1 Introduction2 Approaches toward Umpolung of Enamines3 Umpolung of Enamines through Single-Electron Oxidation4 Azadienes as Synthetic Equivalents of Enamine Umpolung Synthons5 Enamines Possessing a Leaving Group at the Nitrogen Atom6 Enamines Possessing a Directing Group at the Nitrogen Atom7 Summary and Outlook