Carbon-carbon and carbon-nitrogen bond forming events are essential in chemistry. Although numerous stoichiometric/catalytic methods provided elegant and powerful solutions enabling those processes, the use of scarce/toxic reagents and harsh conditions is still ubiquitous in this field. As a result, extensive research has been conducted in the development of environmentally benign and inexpensive reagents for such transformations, however, general solutions remain a challenge. In this context, one of the focuses of our lab is to enable those processes in a more practical and sustainable fashion by using hypervalent iodine reagents. In this dissertation we demonstrate the synthetic applications of λ3-iodane reagents towards the formation of challenging carbon-carbon and carbon-nitrogen bonds in a complementary way to the methods already reported. Chapter 1 of this dissertation outlines the general electronic structure, geometry, synthesis and reactivity of λ3-iodanes as serves and background regarding these reagents. Chapter 2 highlights the applications of λ3-iodanes to access high-oxidation state transition metals until the year of 2017. This literature review provides detailed information about how λ3-iodanes can be applied to access 1st, 2nd and 3rd row high-oxidation complexes, as well as mechanistic details and synthetic utility of high-valent transition metals. Chapter 3 demonstrates our efforts to generate selective carbon-nitrogen and carbon-carbon products from a high-valent nickel complex. This led to important information of this mechanism adopted by the reaction and how the choice of oxidant can impact 1e- versus 2e- oxidative pathways on “hard” nickel pincer scaffolds. Chapter 4 describes our efforts towards the selective formation of α-C(sp2)-C(sp2) bonds at the α-position of enones via a reductive Iodonium-Claisen rearrangement. We demonstrate the utility of β-pyridinium silyl enol ethers as a platform for direct α-arylation, and how the 2-iodo-aryl-α-arylated enones can be used to access diverse heterocyclic structures. Chapter 5 demonstrates our initial efforts towards the selective C2 or C3 carbon-nitrogen bond formation on indoles. By exposing different indoles to (bis)cationic nitrogen-ligated HVI (N-HVI) reagents we found that selective C2 or C3 C-H indole-pyridinium salts can be formed in good to excellent yield. Although, this project is not finished yet, we anticipate the indole-pyridinium salts generated could serve as platform for accessing diverse piperidines, pyridones and primary amines through straightforward procedures. The combined chapters of this dissertation highlight the applications of λ3-iodanes towards transition metals and emphasize the applications of these reagents to enable challenging C–C and C–N bond formation events. More importantly, this dissertation serves as a guide for future development of the hypervalent iodine field. / Chemistry
| Identifer | oai:union.ndltd.org:TEMPLE/oai:scholarshare.temple.edu:20.500.12613/2074 |
| Date | January 2020 |
| Creators | Sousa e Silva, Felipe Cesar |
| Contributors | Wengryniuk, Sarah E., Sieburth, Scott McNeill, Dobereiner, Graham, Hunt, David |
| Publisher | Temple University. Libraries |
| Source Sets | Temple University |
| Language | English |
| Detected Language | English |
| Type | Thesis/Dissertation, Text |
| Format | 607 pages |
| Rights | IN COPYRIGHT- This Rights Statement can be used for an Item that is in copyright. Using this statement implies that the organization making this Item available has determined that the Item is in copyright and either is the rights-holder, has obtained permission from the rights-holder(s) to make their Work(s) available, or makes the Item available under an exception or limitation to copyright (including Fair Use) that entitles it to make the Item available., http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | http://dx.doi.org/10.34944/dspace/2056, Theses and Dissertations |
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