The Ru(CHPh)Cl2(PCy3)2-initiated ring-opening metathesis polymerization of 7-tert-butoxybicyclo[2.2.1]hepta-2,5-diene: regeneration of initiator and the implied formation of macrocycles

Abstract

The ring-opening metathesis polymerization (ROMP) of 7-tert-butoxybicyclo[2.2.1]hepta-2,5-diene initiated by Ru(CHPh)Cl₂(PCy₃)₂ proceeds rapidly in organic solvents with almost complete consumption of initiator to form propagating ruthenium carbene species that are then converted slowly but not completely back to initiator, implying a secondary ring-closing metathesis reaction at the chain ends to form macrocycles.