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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Studies toward the total synthesis of tetramethyldihydroxanthene natural products

Gervais, Anais 12 March 2016 (has links)
Tetramethyldihydroxanthenes constitute a large class of natural products wherein a 6-member ring triketone moiety is linked to an aromatic moiety. Progress toward the syntheses of six biologically active natural products isolated from these genus species; rhodomyrtone A, rhodomyrtosones A and B, tomentosones A and B, and bullataketals A and B, are described. These compounds possess challenging structures and interesting bioactivities making them attractive targets. Isolation, structure elucidation and biosyntheses of rhodomyrtone A, rhodomyrtosone A and B, tomentosones A and B, and bullataketals A and B are discussed. To accomplish their total syntheses, several new methodologies have been developed. A nickel-mediated catalytic 1,4-conjugate addition was developed. Literature precedents showcasing the use of nickel-mediated 1,4-conjugate addition and previously reported nickel-mediated enantioselective catalytic systems are presented herein along with our work. The challenges met during the development of a regioselective dehydrative cyclization for the syntheses of rhodomyrtone A and rhodomyrtosone B are discussed and strategies designed to overcome this synthetic challenge are presented in detail. Our studies to develop a flow photochemistry-mediated process to access endoperoxides, as well as generation and trapping of active vinyloxocarbenium intermediates are presented along with relevant literature precedents.

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