LIGAND-ACCELERATED CATALYSIS

The search for new metal‐catalyzed asymmetric reactions has provided some fascinating insights into the effects imposed on the metal catalysts by chiral ligands. A practical consequence is the discovery of ligand‐accelerated catalysis (LAC). Thus, an existing catalyzed process is improved by the addition of a specific ligand, which leads to a faster, “ligand‐accelerated” reaction. Both homogeneous and heterogeneous catalysts are known to exhibit this behavior. The concept is especially valuable in reactions catalyzed by early transition metals, where dynamic ligand exchange processes require an efficient in situ self‐selection of a highly reactive catalyst from a variety of thermodynamically dictated assemblies. Results of detailed mechanistic studies will be presented, and the significance of LAC phenomena in transformations catalyzed by early and late transition metals will be discussed. Copyright © 1995 by VCH Verlagsgesellschaft mbH, Germany