Ring‐opening metathesis polymerization of 11‐alkylidenebenzonorbornadienes

摘要

Abstract11‐(α‐Phenylbenzylidene)benzonorbornadiene (3) and other similar monomers were synthesized by cycloaddition of dehydrobenzene with different fulvenes. Ring‐opening metathesis polymerization of the resulting monomers using Mo‐carbene initiators gave highly stereoregular polymers. Variation of the substituents allows control of the stereoregularity of these polymers. Poly11‐(α‐phenylbenzylidene)benzonorbornadiene is completelycisconnected, whereas poly11‐(α‐methylbenzylidene)benzonorbornadiene is completelytranslinked. The polymers contain two very reactive carbon‐hydrogen bonds that are both allylic and benzylic. Elimination of these bridgehead hydrogens gives a fully conjugated polymer that can be described as having “fulvenoid