Carbon–carbon bond activation by Mg, Al, and Zn complexes

Examples of carbon–carbon bond activation reactions at Mg, Al, and Zn are described in this review. Several distinct mechanisms for C–C bond activation at these metals have been proposed, with the key C–C bond activation step occurring by (i) α-alkyl elimination, (ii) β-alkyl elimination, (iii) oxidative addition, or (iv) an electrocyclic reaction. Many of the known pathways involve an overall 2-electron redox process. Despite this, the direct oxidative addition of C–C bonds to these metals is relatively rare, instead most reactions occur through initial installation of the metal on a hydrocarbon scaffold (e.g. by a cycloaddition reaction or hydrometallation) followed by an α-alkyl or β-alkyl elimination step. Emerging applications of Mg, Al, and Zn complexes as catalysts for the functionalisation of C–C bonds are also discussed.