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This dissertation concerns the stereoselective synthesis of optically pure compound 196, the C₁₆-C₃₂ fragment of the polyether antibiotic ionomycin (1). Fragment 196 was synthesized by preparing and joining the two subunits 172 (C₁₆-C₂₂) and 122 (C₁₆-C₃₂). Compound 172 was synthesized by repetitive asymmetric aldol condensations of optically pure crotonyl imide 69 with aldehydes 129 and 139. The use of 69 allowed for the enantioselective construction of the two propionate units of fragment 172 having the "anti" configuration. Compound 122 was synthesized using the highly stereospecific oxidative permanganate cyclization of the 1,5-diene 93 to give racemic tetrahydrofuran 94, having the correct relative stereochemistry at the four asymmetric centres. The diene 93 was in turn prepared via the β-keto ester dianion methodology which allows for the stereospecific introduction of the isoprenoid unit. Diol 103, derived from 94 was resolved as its mono (+)- ̲O̲-acetylmandelate and was transformed into optically active fragment 122. Finally, to complete the synthesis of optically active fragment C₁₆-C₃₂ of ionomycin, compounds 172 and 122 were coupled via a Wittig reaction to afford the cis olefin 194 and the second tetrahydrofuran ring of 196 was introduced stereoselectively via an internal oxymercuration reaction. / Science, Faculty of / Chemistry, Department of / Graduate

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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Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Vita. Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Call number: LD2668 .T4 1953 E8 / Master of Science

The synthesis of several 6-Chlorodemethyllavendamycin analogs and their chemistry are described. In this investigation the following compounds were prepared:6-Chlorodemethyllavendamycin methyl ester, 6-Chlorodemethyllavendamycin ethylester, 6-Chlorodemethyllavendamycin butyl ester, 6-Chlorodemethyllavendamycin isoamyl ester, 6-Chlorodemethyllavendamycin octyl ester, and 6-Chlorodemethyllavendamycin amide. Pictet Spengler condensation of 7-amino-6-chloro-2-formylquinoline-5,8-dione with tryptophan methyl ester, tryptophan ethyl ester, tryptophan butyl ester, tryptophan isoamyl ester, tryptophan octyl ester, and tryptophan amide in anisole afforded the compounds. 7-amino-6-chloro-2-formylquinoline-5,8-dione was prepared according to the following general procedures.The first step is the nitration of 8-Hydroxy-2-methylquinoline. 8-Hydroxy-2methylquinoline is reacted with 70% mixture of HNO3/H2SO4 to produce 5,7-dinitro-8hydroxy-2-methylquinoline. The next step requires hydrogenation and acylation. 5,7Dinitro-8-hydroxy-2-methylquinoline was reduced by H2/Pd-C in the presence of HCl and H20 filtered and then treated with sodium sulfite, sodium acetate and acetic anhydride to yield 5,7-diacetamido-8-acetoxy-2-methylquinoline. 5,7-Diacetamido-8-acetoxy-2methylquinoline was oxidized by potassium dichromate to produce 7-acetamido-2methylquinoline-5,8-dione. 7-Acetamido-2-methylquinoline-5,8-dione was chlorinated using hydrogen chloride gas in dry methanol producing 7-amino-6-chloro-2methylquinoline-5,8-dione. Treatment of 7-amino-6-chloro-2-methylquinoline-5,8-dione with selenium dioxide, under reflux in 1,4-dioxane produced 7-amino-6-chloro-2formylquinoline-5, 8-dione.All structures were confirmed by 'H NMR, IR, EIMS, and HRMS. / Department of Chemistry

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published_or_final_version / abstract / Botany / Master / Master of Philosophy