Publications
2005
2004
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
Arene complexes of the form TpM(π-acid)(L)(η2-arene) (Tp = hydridotris(pyrazolyl)borate, M = Re, Mo, or W, π-acid = CO or NO, L = 1-alkylimidazole, pyridine, PMe3, arene is prochiral) exist as a dynamic equilibrium of coordination diastereomers in solution. In both crystalline and amorphous solid states, however, only one diastereomer is present. Reactions on the bound arenes in these complexes have been performed stereoselectively, by exploiting the homomorphic nature of the solid phase.