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You searched for subject:(silanediols). Showing records 1 – 3 of 3 total matches.

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The Ohio State University

1. Visco, Michael David. Chiral Silanediols Designed for Enantioselective Heterocycle Functionalization.

Degree: PhD, Chemistry, 2017, The Ohio State University

Molecular recognition by hydrogen-bond donors has proven to be applicable to various areas of research, including sensing and catalysis. (Thio)ureas have been established as the most conventional and widely studied hydrogen-bond donors, whereas other classes of hydrogen-bond donors, such as silanediols, are much less explored. Although silanediols have been studied in the context of self-recognition as well as, polymerization and materials chemistry, their exceptional hydrogen-bonding ability can also be exploited in catalysis. Prior to our group’s investigations, silanediols had not been demonstrated to participate in asymmetric hydrogen-bond donor catalysis, specifically anion-binding catalysis.Our laboratory was inspired by a report from the Kondo group demonstrating silanediols could recognize an array of anions, such as acetate, bromide and chloride, through hydrogen-bonding. Our curiosities prompted us to explore silanediol anion recognition in the context of asymmetric anion-binding catalysis by developing and synthesizing chiral, enantiopure silanediols. Limited information was available to aid us in the synthesis of chiral silanediols, as there were no reports of silanediols in the area of asymmetric catalysis prior to our research. Consequently, our group has dedicated great efforts to the synthesis and development of chiral silanediols to be utilized in anion-binding catalysis. We have successfully prepared a wide variety of chiral silanediols containing a diverse set of interesting scaffolds and studied their utility in enantioselective functionalization of heterocycles.Having several chiral silanediols on hand, we were eager to investigate their ability to participate in asymmetric anion-binding catalysis. Our initial investigations focused on the enantioselective functionalization of isoquinoline catalyzed by various BINOL-derived silanediols we developed and derivatized. We demonstrated that silanediols could affect the asymmetric addition of silyl ketene acetals to isoquinolinium ions in promising to high levels of enantiomeric excess. Through our investigations we collected valuable data on the physical properties of our silanediols, including pKa values and binding constants to give us insight to future catalyst designs. Most recently our group became interested in the chromanone class of natural products as they are known to exhibit powerful and fascinating biological activity. For example, gonytolide C is a known innate immune promoter and blennolide C exhibits antibacterial properties. Asymmetric intermolecular addition of carbonyl containing nucleophiles in the construction of chromanones had been elusive prior to our studies. We have established chiral silanediol catalysis as a viable method to afford these desired chromanone products through anion-binding catalysis with our developed VANOL- and BINOL-based catalysts. Our ultimate objective is to develop general strategies to construct the chromanone core and related heterocycles in a highly stereoselective manner via asymmetric anion-binding… Advisors/Committee Members: Magliery, Thomas (Advisor).

Subjects/Keywords: Chemistry; Organic Chemistry; silanediols; benzylic silanes; organocatalysis; anion-binding catalysis; chromanone

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APA (6th Edition):

Visco, M. D. (2017). Chiral Silanediols Designed for Enantioselective Heterocycle Functionalization. (Doctoral Dissertation). The Ohio State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=osu1492438099945523

Chicago Manual of Style (16th Edition):

Visco, Michael David. “Chiral Silanediols Designed for Enantioselective Heterocycle Functionalization.” 2017. Doctoral Dissertation, The Ohio State University. Accessed September 23, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492438099945523.

MLA Handbook (7th Edition):

Visco, Michael David. “Chiral Silanediols Designed for Enantioselective Heterocycle Functionalization.” 2017. Web. 23 Sep 2020.

Vancouver:

Visco MD. Chiral Silanediols Designed for Enantioselective Heterocycle Functionalization. [Internet] [Doctoral dissertation]. The Ohio State University; 2017. [cited 2020 Sep 23]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1492438099945523.

Council of Science Editors:

Visco MD. Chiral Silanediols Designed for Enantioselective Heterocycle Functionalization. [Doctoral Dissertation]. The Ohio State University; 2017. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1492438099945523

2. Baldwin, Andrea Michelle. Synthesis and Functionalization of Heterocycles via Non-Covalent Catalysis.

Degree: PhD, Chemistry, 2016, The Ohio State University

Hydrogen-bond donor (HBD) catalysis has emerged as a remarkable platform for the activation of reactants through non-covalent interactions. This class of organocatalysts provides a sustainable alternative to transition metal catalysis and avoids the difficulties associated with trace metal removal. Classically, HBD catalyst interactions proceed in two major pathways: direct activation or anion recognition. Enhanced HBD catalysts that display improved performance under both modes of action allow for the discovery of new reactivity patterns that have previously been unattainable. Two new classes of elegantly designed non-covalent catalysts have been explored in the synthesis and functionalization of heterocycles.Boronate ureas, an internal Lewis acid assisted urea, are particularly well suited for the direct activation of molecules containing nitro-functionality. Donor-acceptor cyclopropanes are useful building blocks in synthetic chemistry due to the electronic nature of the strained ring and the intrinsic functionality. Boronate ureas were applied toward development of the first cycloaddition of nitrones with nitrocyclopropane carboxylates in the presence of an enhanced non-covalent catalyst. The highly functionalized 1,2-oxazinane core synthesized in this single step is a prominent scaffold in many bioactive targets. With this strategy, a small library of oxazinane products has been synthesized in up to 99% yield and 4:1 dr. A second class of enhanced catalysts, silanediols, have a propensity to recognize the ether functionality. This molecular recognition was exploited in the context of direct epoxide activation for carbon dioxide fixation. Typically, with organocatalytic cyclic carbonate formation, very few types of functional groups are able to affect this transformation under mild conditions; often, high temperatures, long reaction times, and high pressures of carbon dioxide are necessary for desired product formation. With only 10 mol % of a silanediol-tetrabutylammonium iodide co-catalyst system, this transformation can be accomplished at room temperature using only one bar of carbon dioxide.Having established the ability of silanediols to work in tandem with anions, chiral silanediols were investigated in enantioselective anion-binding catalysis to construct chromanones. To date, introduction of carbonyl-containing nucleophiles in an intermolecular fashion has only been performed racemically. However, the unique chemical environment accessible with novel chiral silanediols is able to control carbon-carbon bond formation between silyl ketene acetals and benzopyrylium salts generated in situ from chromone derivatives. When coupled with recrystallization, synthetically useful enantioselectivities of up to 74% can be obtained. Importantly, this is the first example of anion-binding catalysis utilizing the benzopyrylium ions of chromenones, as well as an innovative strategy to incorporate complex alkyl functionality directly into the scaffold of chromanones. Advisors/Committee Members: Mattson, Anita (Advisor).

Subjects/Keywords: Organic Chemistry; organocatalysis; hydrogen bond donor catalysis; silanediols; boronate ureas; oxazinanes; carbonates; chromanones; asymmetric catalysis

…50 2.1 Silanediols as a Scaffold for Hydrogen Bond Donor Catalysis… …50 2.1.2 Molecular Recognition Properties of Silanediols… …52 2.1.3 Silanediols as Hydrogen Bond Donor Catalysts… …62 2.3 Silanediols in Cyclic Carbonate Formation… …84 3.1 Silanediols as Enantioselective Anion-Binding Catalysts… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Baldwin, A. M. (2016). Synthesis and Functionalization of Heterocycles via Non-Covalent Catalysis. (Doctoral Dissertation). The Ohio State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=osu1467277822

Chicago Manual of Style (16th Edition):

Baldwin, Andrea Michelle. “Synthesis and Functionalization of Heterocycles via Non-Covalent Catalysis.” 2016. Doctoral Dissertation, The Ohio State University. Accessed September 23, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1467277822.

MLA Handbook (7th Edition):

Baldwin, Andrea Michelle. “Synthesis and Functionalization of Heterocycles via Non-Covalent Catalysis.” 2016. Web. 23 Sep 2020.

Vancouver:

Baldwin AM. Synthesis and Functionalization of Heterocycles via Non-Covalent Catalysis. [Internet] [Doctoral dissertation]. The Ohio State University; 2016. [cited 2020 Sep 23]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1467277822.

Council of Science Editors:

Baldwin AM. Synthesis and Functionalization of Heterocycles via Non-Covalent Catalysis. [Doctoral Dissertation]. The Ohio State University; 2016. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1467277822

3. Wieting, Joshua Merlin. Silanediol-Catalyzed Stereoselective Functionalization of Heterocycles.

Degree: PhD, Chemistry, 2015, The Ohio State University

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… Advisors/Committee Members: Mattson, Anita (Advisor).

Subjects/Keywords: Chemistry; Silanediols; Silanediol; Organocatalysis; Hydrogen Bond Donor Catalysis; Asymmetric Catalysis; Silicon Chemistry

…Publications Schafer, A. G.; Wieting, J. M.; Mattson, A. E. “Silanediols: A New Class of Hydrogen… …Mattson, A. E. “Chiral Silanediols in AnionBinding Catalysis” Angew. Chem. Int. Ed. 2013, 52… …A. E. “Preparation and Catalytic Activity of BINOL-Derived Silanediols” Eur. J. Org. Chem… …1 1.2 Anion-Recognition and Sensing Abilities of Silanediols ..2 1.3 Synthesis of… …Diaryl Silanediols ..4 1.4 Enzyme Active Site Recognition of Silanediols… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Wieting, J. M. (2015). Silanediol-Catalyzed Stereoselective Functionalization of Heterocycles. (Doctoral Dissertation). The Ohio State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=osu1448891366

Chicago Manual of Style (16th Edition):

Wieting, Joshua Merlin. “Silanediol-Catalyzed Stereoselective Functionalization of Heterocycles.” 2015. Doctoral Dissertation, The Ohio State University. Accessed September 23, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1448891366.

MLA Handbook (7th Edition):

Wieting, Joshua Merlin. “Silanediol-Catalyzed Stereoselective Functionalization of Heterocycles.” 2015. Web. 23 Sep 2020.

Vancouver:

Wieting JM. Silanediol-Catalyzed Stereoselective Functionalization of Heterocycles. [Internet] [Doctoral dissertation]. The Ohio State University; 2015. [cited 2020 Sep 23]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1448891366.

Council of Science Editors:

Wieting JM. Silanediol-Catalyzed Stereoselective Functionalization of Heterocycles. [Doctoral Dissertation]. The Ohio State University; 2015. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1448891366

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