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 precatalysts treated with an inexpensive chiral poison. The poison selectively deactivates one enantiomer of the racemic mixture. The remaining active enantiomer is used to catalyze an asymmetric reaction. This general strategy has been demonstrated for asymmetric hydrogenations and Lewis acid-catalyzed Diels-Alder reactions. More effective poisons will be developed and will be applied to the preparation of chiral catalysts for a broad range of asymmetric reactions. 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. The racemization of chiral 16 electron intermediates can potentially decrease the selectivity of asymmetric catalysts. This racemization process and methods of controlling it will also be studied. 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 effective. 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 scientists in the areas of metal catalysis and asymmetric synthesis.