Organic synthesis using homogeneous and heterogeneous transition metal catalysts

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Transition metal catalysts such as those composed of rhodium, platinum and palladium are employed in a variety of processes, inculding catalytic converters in cars.  These same metals are often used in molecular catalysts for the conversion of simple organic molecules into more complex ones.  Metal catalysts in the molecular state are prepared by introducing ligands on the metal which prevent decomposition to the bulk metal.  These ligands can even make a metal like palladium soluble in organic solvents.  The ligands are also employed to adjust the reactivity of the metal.  Chiral ligands can even be used to generate chiral products from achiral starting materials.  This is one of the most efficient methods for the synthesis of chiral products, since only catalytic amounts of the initial chiral material (the chiral ligand) is required.  We have proposed to study three important catalytic processes, the hydroboration of olefins, the oxidation of alcohols and the preparation of carbon-carbon bonds in Suzuki coupling reactions.  Our study of these reactions will focus on the following key points:  understanding the mechanism; expanding the scope of the reaction; introducing chirality; recovering the catalyst.  This latter point is often overlooked since metal catalysts are usually cheaper than the products they are used to produce.  However, not only is it more efficient to be able to recover the catalyst, it is also critical for the purity of the product.  This has become a significant problem in both the pharmaceutical and electronic materials industries where trace amounts of metals can cause significant problems.  In the case of pharmaceutical products, the presence of metals such as Pd and Rh may cause significant toxicity.  In the case of materials, metal contamination can cause shorts in electronic devices, or limit the ability of a material to act as an insulator.  Thus we will also address different strategies to remove metals from reaction mixtures as well as ways to immobilize the complexes so that they do not contaminate the prodcut to begin with.