eprintid: 39853 rev_number: 11 userid: 9841 dir: disk0/00/03/98/53 datestamp: 2021-01-20 19:34:50 lastmod: 2021-01-20 19:34:50 status_changed: 2021-01-20 19:34:50 type: thesis_degree succeeds: 39781 metadata_visibility: show contact_email: ltj6@pitt.edu item_issues_id: thesis_degree_versioning item_issues_type: thesis_degree_versioning item_issues_description: ETD 39853 is using versioning. item_issues_timestamp: 2020-10-10 06:02:22 item_issues_status: discovered item_issues_count: 1 eprint_status: archive creators_name: Jesikiewicz, Luke title: Ligand Effects on Reactivity and Selectivity of Transition-Metal Catalyzed Asymmetric C-C and C-N Bond Forming Reactions ispublished: unpub divisions: sch_as_chemistry full_text_status: restricted keywords: Density Functional Theory, Computational Chemistry, Organic Chemistry, Cross-coupling reaction, Pauson-Khand reaction, Copper, Rhodium abstract: Homogenous catalysis using transition metals has grown to be one of the most common ways of forming chemical bonds in an enantioselective and regioselective manner. The role of the ancillary ligand in these processes is crucial in determining the desired stereochemical outcome. The origins of the effects of ligands that influence reactions to yield a specific product are not yet well understood. Herein, three studies that combine density functional theory (DFT) calculations and experimental data to further understand the role of the ligand in transition metal catalyzed reactions are reported. In the first study, the mechanisms and rate- and selectivity-determining steps of the copper-catalyzed asymmetric coupling of ketones and 1,3-butadiene were examined. The product selectivity is controlled by steric interactions from a combination of chiral ligand-substrate interactions and steric repulsions about the forming carbon-carbon bond in the Zimmerman-Traxler type ketone addition transition state. Next, a mechanistic study of the copper-catalyzed coupling of 1,3-enynes and nitriles demonstrated the selectivity was determined through steric interactions in the nitrile addition and cyclization steps of the reaction. Lastly, the study of the rhodium-catalyzed Pauson-Khand reaction of 1,6-enynes identified a key steric interaction between the substrate and the ligand in the oxidative cyclization transition state that controls the enantioselectivity. Additionally, this study demonstrated the importance of accounting for experimental conditions when performing DFT calculations. Taken together, these computational studies demonstrated the effective use of DFT calculations to study mechanisms, and the effects of ligands and substrates on reactivity and selectivity in transition metal-catalyzed reactions. date: 2020-08-31 pages: 78 institution: University of Pittsburgh refereed: TRUE etdcommittee_type: committee_chair etdcommittee_type: committee_member etdcommittee_type: committee_member etdcommittee_name: Liu, Peng etdcommittee_name: Brummond, Kay M. etdcommittee_name: Laaser, Jennifer etdcommittee_email: pengliu@pitt.edu etdcommittee_email: brummond@pitt.edu etdcommittee_email: j.laaser@pitt.edu etdcommittee_id: pengliu etdcommittee_id: brummond etdcommittee_id: j.laaser etd_defense_date: 2019-12-03 etd_approval_date: 2021-01-20 etd_submission_date: 2020-10-04 etd_release_date: 2021-01-20 etd_access_restriction: 1_year etd_patent_pending: FALSE thesis_type: thesis degree: MS citation: Jesikiewicz, Luke (2020) Ligand Effects on Reactivity and Selectivity of Transition-Metal Catalyzed Asymmetric C-C and C-N Bond Forming Reactions. Master's Thesis, University of Pittsburgh. (Unpublished) document_url: http://d-scholarship-dev.library.pitt.edu/39853/15/Jesikiewicz%20Final%20ETD.pdf