Cobalt-CatalyzedZtoEIsomerization of Alkenes: An Approach to (E)-β-Substituted Styrenes

An efficient cobalt-catalyzed Z to E isomerization of β-substituted styrenes using the amido-diphosphine ligand was developed, delivering the ( E )-isomers with good functional tolerance and high stereoselectivity. The reaction could be scaled up to gram-scale with a catalyst loading of 0.1 mol %, using a mixture of ( Z )- and ( E )-alkene as the starting material. Preliminary mechanistic studies indicated that cobalt(I)-hydride and a benzylic-cobalt species were probably involved in the reaction, as supported by experiments and DFT calculations.