Reactions and Stereochemistry of Organometallic Compounds Related to Asymmetric Synthesis and Catalytic Activity

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Dr. John W. Faller, Chemistry Department, Yale University, is supported by the Inorganic, Bioinorganic, and Organometallic Chemistry Program for studies related to asymmetric and regioselective synthesis and catalysis using metal complexes. New strategies will be developed for asymmetric synthesis based on the use of readily available racemic ligands followed by treatment with an inexpensive chiral poison to selectively deactivate one enantiomer of the racemic mixture. The remaining ligand enantiomer will be employed to prepare chiral metal catalysts. This general strategy has been demonstrated for asymmetric hydrogenations and will be extended to a number of other systems including a series of titanium-alkoxide catalyzed reactions. More effective poisons will be developed and will be applied to the preparation of chiral catalyst for a broad range of asymmetric reactions that have conventionally used noble metal catalysts prepared from enantiomerically pure phosphine ligands. In reactions where dimers are active species, the conventional approach has involved the dimerization of enantiomeric monomers. The possibility of enhancing enantioselectivity through the use of pseudo-enantiomeric complexes, which are composed of bimetallics containing different chiral ligands, will be explored. Hemilabile ligands will be used to control the stereochemistry in catalytic intermediates and to provide stoichiometeric reagents for preparation of homoallylic alcohols by allyl addition to aldehydes. An object which is not the same as its mirror image (e.g. a left compared to a right handed glove) is said to be chiral. Many pharmaceutical and agricultural chemicals are chiral and often only one of the two mirror image molecules is desired. Since it is difficult to obtain a single mirror image, the production of such molecules is an important goal in contemporary chemistry. In this project new strategies toward solving the problem of `asymmetric synthesis` will be applied to a broad range of reactions and new, more economic preparations of important molecules will be developed. In addition to the chemical research, this project has the important objective of training young scientist in the areas of metal catalysis and asymmetric synthesis.