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(C 6 F 5 ) 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 ( Đ as low as 1.12). Furthermore, topology analysis shows that NHC1/B(C 6 F 5 ) 3 LP produce PMS possessing cyclic structure.