Ruthenium-based olefin metathesis catalysts coordinated with thiazol-2-ylidene ligands

INOR 503

Georgios C. Vougioukalakis, vougiouk@caltech.edu and Robert H. Grubbs, rhg@caltech.edu. Division of Chemistry and Chemical Engineering, Arnold and Mabel Beckman Laboratory of Chemical Synthesis, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125
The development of well defined catalysts with good functional group tolerance has established olefin metathesis as a powerful tool for the formation of carbon-carbon double bonds. Substitution of a phosphine for an N-heterocyclic carbene ligand, in ruthenium-based metathesis catalysts, led to more efficient complexes that maintain the high functional group tolerance and air and moisture stability of the phosphine-containing complexes. Nevertheless, the development of catalysts that could efficiently control E/Z selectivity in cross-metathesis reactions, or afford tetrasubstituted double bond products in ring-closing metathesis reactions, still represents a major challenge. The present work focuses on the synthesis of novel ruthenium-based olefin metathesis catalysts bearing a series of thiazol-2-ylidene ligands. Their structure and catalytic activity in ring-closing metathesis, ring-opening metathesis polymerization, and cross-metathesis reactions will be discussed as well.