Highly Regio- and trans-Selective Ring-opening Metathesis Polymerization of Chiral Aza-norbornene with a Simple Phenylimido-Tungsten Catalyst

Abstract

Stereochemical control in ring-opening metathesis polymerization (ROMP) is essential for tailoring polymer properties. While several existing studies have achieved tunable regioselectivity with asymmetric monomers through catalyst design, yet achieving high trans-selectivity alongside defined regiochemistry remains challenging. Here we report the ROMP of a chiral aza-norbornene monomer derived from Vince lactam using a readily prepared phenylimido tungsten catalyst. The resulting polymer exhibited high head-to-head regioselectivity and high trans-selectivity, which stands in stark contrast to our previous work where Ru-based catalysts afforded predominantly cis-selective polymers from the same monomer. Moreover, together with our previously reported polymers, specific rotation measurements and circular dichroism spectra demonstrated that varied stereochemical configurations significantly influenced the optical activity and chiral expression of polymers derived from the same chiral monomer. This work provides a complementary approach to stereochemical control in ROMP, offering valuable insights for design and synthesis of structurally well-defined chiral polymers.