This thesis describes the inception, design, and implementation of stereoselective desymmetrization reactions in the total synthesis of the natural products pactamycin and paspaline. In the case of pactamycin, the author develops a novel asymmetric Mannich reaction and symmetry-breaking reduction strategy to enable facile construction of the complex core architecture in fifteen steps using commercially available materials the shortest synthesis to date. He subsequently demonstrates the flexibility of this approach in SAR investigations by highlighting the preparation of twenty-five unique...