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Title Silanediol-Catalyzed Stereoselective Functionalization of Heterocycles
URL
Publication Date
Degree PhD
Discipline/Department Chemistry
Degree Level doctoral
University/Publisher The Ohio State University
Abstract 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…
Subjects/Keywords Chemistry; Silanediols; Silanediol; Organocatalysis; Hydrogen Bond Donor Catalysis; Asymmetric Catalysis; Silicon Chemistry
Contributors Mattson, Anita (Advisor)
Language en
Rights unrestricted ; This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
Country of Publication us
Format application/pdf
Record ID oai:etd.ohiolink.edu:osu1448891366
Repository ohiolink
Date Indexed 2020-10-19
Grantor The Ohio State University

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