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Columbia Dissertations and Theses > Doctoral Dissertations
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| Author(s): | Meng, Zhaoyang |
| Title: | 1. Asymmetric synthesis of merrilactone A. 2. Studies toward the total synthesis of pinnamine. |
| Advisor(s): | Danishefsky, Samuel J. |
| Physical Description: | 154 p. |
| Issue Date: | 2006 |
| Description: | Source: Dissertation Abstracts International, Volume: 66-12, Section: B, page: 6632. Adviser: Samuel J. Danishefsky. Thesis (Ph.D.)--Columbia University, 2006. |
| Bookmark as: | http://hdl.handle.net/10022/AC:P:7605 |
| Full Text (ProQuest): | /ac/proxit.jsp?url=http://gateway.proquest.com/ope... |
| Abstract: | The first part of the dissertation describes the asymmetric synthesis of the merrilactone A, an anislactone-type sesquiterpene consisting of the highly oxygenated pentacyclic skeleton with one oxetane, two gamma-lactones, seven successive stereogenic centers and five quaternary centers. The discovery, structure determination, biosynthesis, unique neurotrophic activity and previous synthetic studies of merrilactone A are discussed. A route to optically active merrilactone A has been developed. The new synthetic route serves the dual purpose of allowing access to enantiomerically enriched material and of providing a means to overcome weaknesses that had been identified in the first generation racemic synthesis. Highlights of the sequence are the stereospecific C-methylation, highly regioselective Baeyer-Villiger reaction, and carboxy-inversion. The key reaction for successful enantioselective synthesis is the asymmetric intramolecular ring opening methodology (ARO) developed by Jacobsen and co-workers. Either antipode of merrilactone A could be accessed by simply switching the Jacobsen's catalyst. The second part presents my efforts toward the total synthesis of the marine alkaloidal toxin: pinnamine. After a brief introduction of the isolation and structure assignment and review of synthetic works from other groups, our approach to the synthesis of pinnamine via a hetero-Diels-Alder reaction followed by the final ring closure step involving an N-acyliminium ion intermediate is presented. The intramolecular Mannich reaction is proved to be not easy. Our proposed solution to this issue is also discussed. |
| Collection(s): | Doctoral Dissertations |
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