Synthesis of air‐stable poly(benzonorbornadiene)s via ring‐opening metathesis polymerization

Herein, air‐stable poly(benzonorbornadiene) was synthesized via ring‐opening metathesis polymerization. Conventional poly(benzonorbornadiene) easily decomposed in the presence of molecular oxygen owing to the generation of radicals at allylic and benzylic hydrogens. However, our sterically bulky aryl‐group substituents of polymers physically blocked the access of oxygen at these positions. The resulting polymers preserved their backbones for more than 2 weeks in air. Postmodification of bromophenyl‐substituted polymer successfully afforded the expanded aryl substituted polymer by Suzuki‐Miyaura coupling with phenylboronic acid in the presence of Pd catalyst. With this highly air‐stable polymers, development of fully conjugated all‐carbon polymer is currently being studied.