“…Polymerizations based on olefin metathesis, such as acyclic diene metathesis (ADMET) , and ROMP, represent a promising and versatile strategy to access a diverse pool of stereodefined polyalkenamers because of the robustness, functional-group tolerance, and structural diversity of metathesis catalysts. , Specifically designed W or Mo alkylidenes were found to overcome the thermodynamic preference of ROMP and to deliver high cis selectivity mostly with nonpolar monomers via kinetic control. , The recent development of Z -selective − and stereoretentive − Ru catalysts has allowed the expansion of the scope of cis -selective ROMP processes. − Interestingly, while ADMET is a powerful tool for the precise synthesis of polymers, , control over the stereochemistry of the repeating alkenes has long escaped this versatile polymerization.…”