Transition metal catalyst. Prepn: P. Schwab et al., Angew. Chem. Int. Ed. 34, 2039 (1995); and of related catalysts: eidem, J. Am. Chem. Soc. 118, 100 (1996). Ring-closing metathesis intoduction of carbon-carbon crosslinks in peptides: S. J. Miller et al., ibid. 9606. Mechanism of ring-opening metathesis: J. A. Tallarico et al., ibid. 119, 7157 (1997). Yne-ene cross metathesis: M. Schuster, S. Blechert, Tetrahedron Lett. 39, 2295 (1998). Review of use and prepn: A. Fürstner, Angew. Chem. Int. Ed. 39, 3012-3043 (2000).