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I. The Asymmetric Total Synthesis of Apratoxin D II. Studies in the Gold(I)-Catalyzed Cycloisomerization of 7-Aryl-1,6-Enynes. III. Synthesis and Application of Multidentate Ligands Toward the Realization of Fluxional Mechanocatalysis

dc.contributor.advisor Widenhoefer, Ross A
dc.contributor.author Robertson, Bradley
dc.date.accessioned 2016-01-04T19:26:15Z
dc.date.available 2017-12-02T05:30:06Z
dc.date.issued 2015
dc.identifier.uri http://hdl.handle.net/10161/11348
dc.description.abstract <p>Apratoxin D, recently isolated from two species of cyanobacteria, L. majuscula and L. sordida, exhibits highly potent in vitro cytotoxicity against H-­‐‑460 human lung cancer cells with an IC50 value of 2.6 nM. The potent biological activity exhibited by apratoxin D combined with its intriguing molecular architecture has led to the pursuit of its asymmetric total synthesis. Studies toward and completion of the first asymmetric total synthesis of apratoxin D are reported. Key transformations include a Kelly thiazoline formation, Paterson anti-­‐‑aldol and an Evans syn-­‐‑aldol. The synthesis was completed in 2.1% total yield over 31 steps from (R)-­‐‑citronellic acid.</p><p>Cationic gold (I) complexes are highly efficient catalysts for the cycloisomerization of 1,6-­‐‑enynes, a transformation capable of providing a great amount of structural complexity from simple starting materials. The in situ spectroscopic analysis of the catalytic cycloisomerization of a 7-­‐‑phenyl-­‐‑1,6-­‐‑enyne, as well as the tandem gold/silver-­‐‑catalyzed cycloaddition/hydroarylation of 7-­‐‑aryl-­‐‑1,6-­‐‑enynes is described. The cycloaddition/hydroarylation reaction provides 6,6-­‐‑ diarylbicyclo[3.2.0]heptanes in good yield under mild conditions. Experimental observations point to a mechanism involving gold-­‐‑catalyzed cycloaddition followed by silver-­‐‑catalyzed hydroarylation of a bicyclo[3.2.0]hept-­‐‑1(7)-­‐‑ene intermediate.</p><p>The control of bond scission and formation by mechanocatalysis has potential in a variety of applications, including biomedical devices, mechanical sensors and self-­‐‑</p><p>6</p><p>healing materials. The synthesis and study of C2-­‐‑symmetric bis(phosphine) ligands with applications toward mechanocatalysis is described. Additionally, the synthesis and study of a tetradentate ligand designed toward mechanochemical activation of a latent catalytic complex is reported. These studies have allowed further development in the design of transition metal complexes capable of activation by mechanical force.</p>
dc.subject Chemistry
dc.subject Organic chemistry
dc.title I. The Asymmetric Total Synthesis of Apratoxin D II. Studies in the Gold(I)-Catalyzed Cycloisomerization of 7-Aryl-1,6-Enynes. III. Synthesis and Application of Multidentate Ligands Toward the Realization of Fluxional Mechanocatalysis
dc.type Dissertation
dc.department Chemistry
duke.embargo.months 23


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