Conformational and linkage isomerizations for dihapto-coordinated arenes and aromatic heterocycles: controlling the stereochemistry of ligand transformations

Arenes and aromatic heterocycles have cyclic skeletons made up completely of unsaturated carbons. Through their dihapto coordination to a transition metal, controlled addition reactions can be accomplished with good stereocontrol, relative to the position of the metal. The metal can readily undergo inter- and intrafacial linkage isomerizations in these complexes. By controlling these processes using chiral auxiliaries on the arene, stereogenic metal centers, or solid-state induced control of kinetically unstable stereoisomers (SICKUS), enantio-enriched organic compounds can be realized from this methodology. This work outlines what is known about conformational and linkage isomerizations in dihapto-coordinated aromatic complexes, and demonstrates their relevance to organic synthesis. (C) 2004 Elsevier B.V. All rights reserved.