The Ru([double bond, length half m-dash]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([double bond, length half m-dash]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.

References

1. J. G. Hamilton and J. J. Rooney, J. Chem. Soc., Chem. Commun., 1992, 370.
2. P. Schwab, M. B. France, J. W. Ziller and R. H. Grubbs, Angew. Chem., Int. Ed. Engl., 1995, 34, 2039.
3. K. J. Ivin and J. C. Mol, Olefin Metathesis and Metathesis Polymerization, Academic Press, London 1997, p. 232.
4. S. T. Nguyen, L. K. Johnson, R. H. Grubbs and J. W. Ziller, J. Am. Chem. Soc., 1992, 114, 3974.
5. S. T. Nguyen, R. H. Grubbs and J. W. Ziller, J. Am. Chem. Soc., 1993, 115, 9858.
6. Z. Wu, A. D. Benedicto and R. H. Grubbs, Macromolecules, 1993, 26, 4975.
7. B. R. Maughon and R. H. Grubbs, Macromolecules, 1997, 30, 3459.