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

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The Ohio State University

1. Dunham, Veronica Vin-yi. Metal-Free Approaches to Sterically-Hindered Bonds.

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

Developing methods to perform cross coupling reactions by means of catalysis is highly desirable in chemistry. Many industries in today’s society, such as the petroleum, agriculture, pharmaceutical, electronics, and polymer industry, use catalysis to some extent whether it is to make molecules that offer crop protection or toward the synthesis of the active ingredient of a medication. It is noteworthy that over 90% of chemicals are made through catalytic processes and that the catalyst market reached $17 billion in 2014, which demonstrates the demand for such methods. While transition metal catalysts have advantages such as low catalyst loading, broad reactivity, and that they have been well studied, some disadvantages are that they can be relatively expensive and sometimes air sensitive which can make them challenging to use. Organocatalysis, specifically non-covalent catalysis operating through hydrogen bond donating interactions, offers an environmentally-friendly alternative to transition metal catalysis. Our lab utilizes organocatalysis as a strategy to synthesize challenging, sterically-hindered bonds.Nitrimines have been identified as powerful coupling partners for the sustainable construction of new sterically congested carbon-carbon and carbon-heteroatom bonds. Using urea catalysis, a metal-free method to synthesize previously inaccessible enamines has been developed. Conventional routes to synthesize enamines as important building blocks toward target molecules generally require Lewis/Brønsted acids or expensive transition metals; however, these methods are often unsuccessful when sterically-hindered substrates are used. To address this synthetic challenge, it was hypothesized that hydrogen bonding interactions between a urea organocatalyst and nitrimine would generate a reactive species suited for the effective carbon-nitrogen coupling with amines to give the desired enamine products. This reaction provides high yields (up to 99%) of enamines using a variety of nitrimines and amines including piperidine, pyrrolidine, dibenzylamine, substituted indolines, and substituted N-methylanilines.Further investigations into the applicability of nitrimines for the synthesis of sterically-hindered bonds led to the discovery of formal carbon-carbon cross coupling reactions involving nitrimines and carbon nucleophiles such as indole, pyrrole, and hydroxycoumarin. Under optimized conditions, moderate to high yields of the desired di- or tri-substituted alkene product were obtained with electron-rich and electron-poor nitrimines. Furthermore, by strategic modification of the reaction conditions, control over the E/Z selectivity of the tri-substituted alkene products gave up to 19:1 ratio of Z:E isomers. This nitrimine-based formal carbon-carbon cross coupling methodology was then applied to the synthesis of a small target molecule, phenprocoumon, which was obtained in an overall 67% yield.The undeniable utility of urea catalysis operating through hydrogen bond donor (HBD) interactions has prompted the examination into… Advisors/Committee Members: Mattson, Anita (Advisor).

Subjects/Keywords: Chemistry; nitrimine; organocatalysis; urea catalysis; silanediol; chromanone; heterocycles; metal-free reactions

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

APA (6th Edition):

Dunham, V. V. (2016). Metal-Free Approaches to Sterically-Hindered Bonds. (Doctoral Dissertation). The Ohio State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=osu1467360601

Chicago Manual of Style (16th Edition):

Dunham, Veronica Vin-yi. “Metal-Free Approaches to Sterically-Hindered Bonds.” 2016. Doctoral Dissertation, The Ohio State University. Accessed August 07, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1467360601.

MLA Handbook (7th Edition):

Dunham, Veronica Vin-yi. “Metal-Free Approaches to Sterically-Hindered Bonds.” 2016. Web. 07 Aug 2020.

Vancouver:

Dunham VV. Metal-Free Approaches to Sterically-Hindered Bonds. [Internet] [Doctoral dissertation]. The Ohio State University; 2016. [cited 2020 Aug 07]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1467360601.

Council of Science Editors:

Dunham VV. Metal-Free Approaches to Sterically-Hindered Bonds. [Doctoral Dissertation]. The Ohio State University; 2016. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1467360601


The Ohio State University

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

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 August 07, 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. 07 Aug 2020.

Vancouver:

Visco MD. Chiral Silanediols Designed for Enantioselective Heterocycle Functionalization. [Internet] [Doctoral dissertation]. The Ohio State University; 2017. [cited 2020 Aug 07]. 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


University of Toronto

3. Tremblay, Marc. Microwave-assisted Thermolysis of ortho-substituted Aroylsilanes.

Degree: 2008, University of Toronto

Microwave-Assisted Thermolysis of ortho-Substituted Aroylsilanes Marc Tremblay Master of Science Department of Chemistry University of Toronto 2008 The microwave-assisted thermolysis of ortho-substituted aroylsilanes has been investigated. When irradiated at 250ºC in DMSO or o‑dichlorobenzene for 10 minutes, aroylsilanes form siloxycarbenes that react following different pathways depending on the solvent and the structure of the starting material. It is shown that in the case of substrates having an O‑allyl or an O‑propargyl chain ortho to the acylsilane, cycloaddition occurs followed by a cascade ring opening to give respectively chroman‑4-one and chromen‑4-one derivatives in up to 66% yield. Among the major competitive pathways were the insertion of the siloxycarbene into allylic C–H bonds and decomposition of the acylsilane group to the corresponding aldehyde, followed by Claisen rearrangement.

MAST

Advisors/Committee Members: Dong, Vy Maria, Chemistry.

Subjects/Keywords: acylsilanes; Brook rearrangement; cyclopropanation; cyclopropane; siloxycarbenes; thermolysis; aroylsilanes; microwaves; carbenes; cyclopropenation; cyclopropenes; chromanone; C-H insertion; 0490

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

APA (6th Edition):

Tremblay, M. (2008). Microwave-assisted Thermolysis of ortho-substituted Aroylsilanes. (Masters Thesis). University of Toronto. Retrieved from http://hdl.handle.net/1807/11168

Chicago Manual of Style (16th Edition):

Tremblay, Marc. “Microwave-assisted Thermolysis of ortho-substituted Aroylsilanes.” 2008. Masters Thesis, University of Toronto. Accessed August 07, 2020. http://hdl.handle.net/1807/11168.

MLA Handbook (7th Edition):

Tremblay, Marc. “Microwave-assisted Thermolysis of ortho-substituted Aroylsilanes.” 2008. Web. 07 Aug 2020.

Vancouver:

Tremblay M. Microwave-assisted Thermolysis of ortho-substituted Aroylsilanes. [Internet] [Masters thesis]. University of Toronto; 2008. [cited 2020 Aug 07]. Available from: http://hdl.handle.net/1807/11168.

Council of Science Editors:

Tremblay M. Microwave-assisted Thermolysis of ortho-substituted Aroylsilanes. [Masters Thesis]. University of Toronto; 2008. Available from: http://hdl.handle.net/1807/11168

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