Development of methodologies for asymmetric synthesis and drug discovery

evelopment and optimization of asymmetric catalysts, while requiring an understanding of the catalytic mechanism as well as significant design, is a time-consuming process that requires considerable screening of different metals, chiral ligands and reaction conditions. Chapter one of this dissertation describes our advance toward applying, combinatorial strategies to the development and optimization of asymmetric catalyst in order to expedite this process. We have developed a general solid-phase strategy for the preparation of 2-pyrrolidinylmethanol ligand class and have demonstrated that the synthesized ligands can be evaluated directly for enantioselective additions of diethylzine to aldehydes after cleavage from the support and without purification. These results suggest that combinatorial strategies can be applied to the development of ligand structures for asymmetric catalysis. This work represents the earliest effort in this field.;Chapter two of this dissertation describes an efficient library synthesis strategy by integrating structure-based design and combinatorial chemistry. The structure-based design was used to select building blocks for combinatorial preparation biased towards the target. After synthesis and screening of a directed library with the building blocks selected by structure-based design followed by a non-exhaustive second generation library of only 39 compounds, several nanomolar non-peptide inhibitors of cathepsin D were identified. This general strategy is anticipated to be applied to many other enzyme classes as well.;Chapter three of this dissertation describes a three-step, efficient, and practical asymmetric synthesis of the low molecular weight (MW = 121 Da) tert-butanesulfinamide chiral auxiliary. The key step is asymmetric catalytic oxidation of commercially available, inexpensive tert-butyl disulfide to provide a tert-butyl tert-butanethiosulfinate intermediate. The reaction has been reproducibly carried out on one mole scale. The utility of optically pure tert-butyl tert-butanethiosulfinate for synthesis of other compounds such as tert-butyl sulfoxides and tert-butanesulfinimines is also demonstrated.;Chapter four of this dissertation describes the application of the tert-butanesulfinamide auxiliary to the preparation of tert-butanesulfinimines and further applications of these versatile nitrogen intermediates for asymmetric synthesis of amines. Structurally diverse tert-butanesulfinimines have been synthesized in high yields by direct condensation of tert-butanesulfinamide with aldehydes and ketones. A general, practical and efficient method for synthesis of chiral amines, in particular...