Ring‐Opening Metathesis Polymerization of a Macrobicyclic Olefin Bearing a Sacrificial Silyloxide Bridge

Abstract

AbstractRing‐opening metathesis polymerization (ROMP) has been regarded as a powerful tool for sequence‐controlled polymerization. However, the traditional entropy‐driven ROMP of macrocyclic olefins suffers from the lack of ring strain and poor regioselectivity, whereas the relay‐ring‐closing metathesis polymerization inevitably brings some unnecessary auxiliary structure into each monomeric unit. We developed a macrobicyclic olefin system bearing a sacrificial silyloxide bridge on the α,β′‐positions of the double bond as a new class of sequence‐defined monomer for regioselective ROMP. The monomeric sequence information is implanted in the macro‐ring, while the small ring, a 3‐substituted cyclooctene structure with substantial ring tension, can provide not only narrow polydispersity, but also high regio‐/stereospecificity. Besides, the silyloxide bridge can be sacrificially cleaved by desilylation and deoxygenation reactions to provide clean‐structured, non‐auxiliaried polymers.