Boron-Based Lewis Pairs Catalyzed Living, Regioselective, and Topology-Controlled Polymerization of (E, E)-Alkyl Sorbates

It remains as a great challenge to realize living and controlled polymerization of renewable monomers by the boron-based Lewis pairs. Here, strong nucleophilic N-heterocyclic olefins (NHOs) or N-heterocyclic carbenes (NHCs) as Lewis bases, and boron-based compounds as Lewis acids, are employed to construct LPs for polymerization of alkyl sorbates, including (E, E)-methyl sorbate and (E, E)-ethyl sorbate. Systematic investigation reveals that the combinations of B(C6F5)(3) with appropriate acidity and steric hindrance, and strong nucleophilic NHOs promote living and controlled polymerization of alkyl sorbates in 100% 1,4-addition manner, furnishing polymers with predicted molecular weight (M-w up to 56.6 kg mol(-1)) and narrow molecular weight distribution (D as low as 1.12). Furthermore, topology analysis shows that NHC1/B(C6F5)(3) LP produce PMS possessing cyclic structure.

Automated summary

Realizing living and controlled polymerization of renewable monomers using boron-based Lewis pairs remains a great challenge. In this study, strong nucleophilic N-heterocyclic olefins (NHOs) or N-heterocyclic carbenes (NHCs) as Lewis bases, and boron-based compounds as Lewis acids were used to construct LPs for polymerization of alkyl sorbates. The results show that specific combinations of B(C6F5)(3) with appropriate acidity and steric hindrance, along with strong nucleophilic NHOs, promote living and controlled polymerization of alkyl sorbates, leading to polymers with predicted molecular weight and narrow molecular weight distribution.