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Joshua M. Wieting_Dissertation.pdf (15.6 MB)

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Silanediol-Catalyzed Stereoselective Functionalization of Heterocycles

Wieting, Joshua Merlin
http://orcid.org/0000-0002-7648-2611
http://rave.ohiolink.edu/etdc/view?acc_num=osu1448891366

Abstract Details

2015, Doctor of Philosophy, Ohio State University, Chemistry.
Small molecules that participate in molecular recognition via hydrogen bonding interactions provide a powerful platform for a host of applications. It has been established that these types of molecules can function as therapeutic agents, anion sensors, and organocatalysts. Advancements upon the state of the art in these areas can be realized by developing functional groups that have yet to be explored in the context of hydrogen bond donor molecular recognition such as silanediols. Although silanediols have been investigated in the context of self-assembly and have a long history of serving as monomers in materials chemistry, examples of silanediol based therapeutic agents and anion sensors have only recently been described in the literature. At the outset of our research program, there had been no reports of silanediols participating in hydrogen bond donor catalysis. The silanediol functionality offers a unique scaffold for the construction of a novel class of hydrogen bond donor catalysts. Guanidine, urea, and thiourea moieties make up a majority of the early dual hydrogen bond donor catalysis literature. It was then discovered that squaramides functioned well as hydrogen bond donor catalysts, and in some cases, provided improvement over more traditional (thio)urea catalysis. While numerous research programs existed aimed at improving the activity of (thio)urea hydrogen bond donor catalysts via manipulation of the substituents neighboring to the (thio)urea core, the introduction of squaramides demonstrated that gains could be made by changing the functional group at the heart of the catalyst design. We proposed silanediols would be a new class of enhanced hydrogen bond donor catalyst based on inherent shape, solubility, acidity, and other molecular recognition properties unique to the silanediol. Inspiration for this approach was provided by a 2006 report from the Kondo lab in which they reported a dinaphthylsilanediol that was capable of binding to acetate, chloride, and bromide anions in solution. X-ray crystallography also showed dinaphthylsilanediol formed a 1:1 hydrogen-bonding complex with chloride via the silanediol functionality. Our laboratory explored dinaphthylsilanediol in the context of organic catalysis and discovered it was capable of providing enhanced yields of indole additions to nitroolefins when compared to traditional (thio)urea catalysts under optimized reaction conditions. Another important part of this work was the synthesis of a chiral racemic silanediol catalyst based on an axially chiral backbone derived from 2,2’-dibromo-1,1’-binaphthalene (DBBN). This report provided proof of concept and laid the foundation for building a research program designed to develop silanediols into a new class of enhanced hydrogen bond donor catalysts. After demonstrating silanediols indeed functioned as effective hydrogen bond donor catalysts, our attention turned to rendering the catalyst chiral and enantiopure. The details surrounding the development and application of this novel chiral catalyst makes up the majority of this thesis work. We have been able to synthesize and evaluate a number of chiral silanediols acting as catalysts in enantioselective functionalization of isoquinoline and chromenone heterocycles. We are also at the early stages of showcasing all we’ve learned by synthesizing a complex biologically active molecule, gonytolide A.
Anita Mattson, Ph.D. (Advisor)
Forsyth Craig, Ph.D. (Committee Member)
Nagib David, Ph.D. (Committee Member)
205 p.
Chemistry
Silanediols; Silanediol; Organocatalysis; Hydrogen Bond Donor Catalysis; Asymmetric Catalysis; Silicon Chemistry

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Citations

  • Wieting, J. M. (2015). Silanediol-Catalyzed Stereoselective Functionalization of Heterocycles [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1448891366

    APA Style (7th edition)

  • Wieting, Joshua. Silanediol-Catalyzed Stereoselective Functionalization of Heterocycles. 2015. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1448891366.

    MLA Style (8th edition)

  • Wieting, Joshua. "Silanediol-Catalyzed Stereoselective Functionalization of Heterocycles." Doctoral dissertation, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1448891366

    Chicago Manual of Style (17th edition)

osu1448891366
223
© 2015, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.