Studies toward the total synthesis of a highly potent cytotoxic marine natural product, phorboxazole A, were conducted and resulted in a route to an advanced intermediate, C4-C32, for this purpose. A key feature of our approach is the stereoselective synthesis of two cis-2,6-disubstituted tetrahydropyrans present in the macrolide portion of phorboxazole A by palladium (II) mediated intramolecular alkoxy carbonylation. This provided the C20-C32 and C9-C19 tetrahydropyran subunits of phorboxazole A. An attempt at diastereoselective formation of the third C5-C9 trans-2,6-disubstituted tetrahydropyran by hydride reduction of a C9 hemiketal was complicated by reduction of the C7 exocyclic olefin. However, the C5-C9 tetrahydropyran was constructed by an intramolecular etherification sequence using a novel allylsilane as the source of C4-C8 of the macrolactone. The studies carried out in the course of this thesis have set in place a major segment of the phorboxazole A structure; they require only the addition of the C1-C3 unit and minor functional group modifications to complete the macrolide portion of the molecule. / Graduation date: 2004