Thesis (Masters)--California Institute of Technology, 1983. / Advisor names found in the Acknowledgments pages of the thesis. Title from home page. Viewed 02/09/10. Includes bibliographical references.

The synthesis of 10,10-dimethyltridecanolide (42) was achieved via a fifteen-step sequence in 9% overall yield. The hydrolysis of macrolides 42, 35, and ester 109 was used to probe the conformational behavior of macrolide 42. The results of this study were rationalized through molecular mechanics (MM2) calculations of conformations for macrolide 42. MM2 studies confirmed initial conformational analyses that macrolide 42 should exist predominantly in the [3434] conformation 42a. More importantly, they also revealed the existence of a [3344] conformation 42f. Hydrolysis studies showed that macrolides 42 and 35 hydrolyzed more slowly than ester 109 due to the steric effect of the intermediates. They also suggested that the minor conformation 42f very likely controlled the hydrolysis process of macrolide 42. [Formula Omitted] / Science, Faculty of / Chemistry, Department of / Graduate

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Graduation date: 1997

Graduation date: 1992

More than 30 members of the diverse amphidinolide family of biologically active macrolides have been isolated over last three decades. From this family, amphidinolides C and F stand among the most complex and densely functionalized affiliates. Recently, we have accomplished the first total synthesis of amphidinolide F. The all-carbon framework of amphidinolide C has been synthesized. During endeavor toward the total syntheses of amphidinolides F / C, we have uncovered a "hidden symmetry element" present in the northern and southern domains of amphidinolides F / C. The southern C₁-C₈ and northern C₁₈-C₂₅ tetrahydrofuran segments were derived from a common intermediate. A scalable silver-catalyzed isomerization / cyclization on propargyl-benzoate / diol furnished the common intermediate in multigram quantity. The common intermediate provided access to over half of carbon backbone of the macrocycle as well as majority of stereochemistry present in amphidinolides F / C. Two strategically different techniques have been developed for the C₉-C₁₁ diene preparation. A metal-catalyst free Weinreb amide-vinyl lithium coupling / methylenation sequence furnished the diene motif. Alternately, diastereoselective addition of a dienyl iodide derived 2-lithio-1,3-diene species to an α-oxy aldehyde installed the C₉-C₁₁ diene and secured the C₈ stereochemistry in single operation. The dienyl iodide was prepared via a regioselective hydrostannylation on an enyne. A challenging alkylation between an α-branched sulfone and an α-silyloxy iodide generated the all-carbon frameworks of amphidinolides F / C. An efficient oxidative desulfurization incorporated the carbonyl moiety at C₁₅. The protecting group on C₁₈ alcohol was found to have significant effect on the sulfone-iodide alkylation / oxidative desulfurization sequence. Installation of chelating ethoxyethyl ether on C₁₈ alcohol helped the successful incorporation of C₁₅ ketone and solved the deprotection problem in advanced stage of synthesis. A detailed analytical and computational study on proline sulfonamide-catalyzed aldol reactions has been performed. The pKa value of a proline sulfonamide catalyst was determined experimentally via NMR titration technique. Computational study revealed the origin of enhanced stereoselectivity by proline sulfonamide catalysts over parent proline. The non-classical hydrogen bonding interactions were found to be responsible for improved diastereoselectivity. / Graduation date: 2013

Thesis (M.S.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 140-168).