Synthesis of nitrogen-containing molecules by zinc-catalyzed [4+2] cycloaddition and photoredox-catalyzed C-H functionalization
| dc.contributor.author | Chu, John Chun Kit, author | |
| dc.contributor.author | Rovis, Tomislav, advisor | |
| dc.contributor.author | Kennan, Alan, committee member | |
| dc.contributor.author | Prieto, Amy, committee member | |
| dc.contributor.author | Kanatous, Shane, committee member | |
| dc.date.accessioned | 2017-06-09T15:41:01Z | |
| dc.date.available | 2017-06-09T15:41:01Z | |
| dc.date.issued | 2017 | |
| dc.description.abstract | This work first describes an enantioselective Zn-catalyzed [4+2] cycloaddition of 1-azadienes and nitro-alkenes for the synthesis of medicinally valuable piperidines. The detrimental coordination of 1-azadienes to the Zn catalysts undermines the stereochemical control of the reaction. Fortunately, a novel bisoxazoline ligand limits this undesired coordination and delivers high stereoselectivity. Mechanistic studies suggest the reaction proceeds via a stepwise mechanism in which aza-Michael addition is followed by cyclization. This proposed mechanism also explains the successful cycloaddition between two electron-deficient reaction partners. Secondly, amide-directed carbon-carbon bond formation at unactivated sp3 C-H bonds has been achieved using photoredox catalysis. The reaction features a hydrogen atom abstraction from the C-H bond to a nitrogen radical generated from the amidyl N-H bond, leading to formation of a carbon-centered radical. Trapping of the resulting alkyl radical with an electrophilic alkene gives the desired C-C bond formation. Experimental evidence supports the generation of the nitrogen radical through a stepwise deprotonation/oxidation event in a closed catalytic cycle. The potential to incorporate other functionalities in the C-H bonds, as well as g functionalization of carbonyl compounds, is disclosed. | |
| dc.format.medium | born digital | |
| dc.format.medium | doctoral dissertations | |
| dc.identifier | Chu_colostate_0053A_14038.pdf | |
| dc.identifier.uri | http://hdl.handle.net/10217/181323 | |
| dc.language | English | |
| dc.language.iso | eng | |
| dc.publisher | Colorado State University. Libraries | |
| dc.relation.ispartof | 2000-2019 | |
| dc.rights | Copyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright. | |
| dc.subject | cycloaddition | |
| dc.subject | nitrogen-containing molecules | |
| dc.subject | zinc | |
| dc.subject | hydrogen atom transfer | |
| dc.subject | C-H functionalization | |
| dc.subject | radical | |
| dc.title | Synthesis of nitrogen-containing molecules by zinc-catalyzed [4+2] cycloaddition and photoredox-catalyzed C-H functionalization | |
| dc.type | Text | |
| dcterms.rights.dpla | This Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). | |
| thesis.degree.discipline | Chemistry | |
| thesis.degree.grantor | Colorado State University | |
| thesis.degree.level | Doctoral | |
| thesis.degree.name | Doctor of Philosophy (Ph.D.) |
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