The Electron-Way: Metal-Catalyzed Reductive Umpolung Reactions of Saturated and α,β-Unsaturated Carbonyl Derivatives

Reductive umpolung reactions of saturated and unsaturated carbonyl compounds enable the direct synthesis of 1,2-, 1,4-, 1,6-, etc. substituted carbon frameworks that are difficult to access by other methodologies. Herein, the evolution from stoichiometric to catalytic processes with high chemo-, regio- and stereoselectivity is discussed for each carbon-carbon bond connection type. At certain points, summaries of the known reaction conditions and discussions of the underlying mechanisms are included.