cis -Selective Acyclic Diene Metathesis Polymerization of α , ω -Dienes.

The cis / trans stereochemistry of repeating alkenes in polymers provides a powerful handle to modulate the thermal and mechanical properties of these soft materials, but synthetic methods to precisely dictate this parameter remain scarce. We report herein a cis -selective acyclic diene metathesis (ADMET) polymerization of readily available α,ω-diene monomers with high functional group tolerance. Identification of a highly stereoselective cyclometalated Ru catalyst allowed the synthesis of a broad array of polymers with cis contents up to 99%. This platform was leveraged to study the impact of the cis geometry on the thermal and mechanical properties of polyalkenamers, including an ABA triblock copolymer synthesized via extension of a cis -rich telechelic polyoctenamer with d,l-lactide. These results suggest that cis -selective ADMET affords an efficient strategy to tune the properties of a variety of polymers.