Copper(II) 2-Quinoxalinol Salen Type Ligands as Catalysts for C-H Oxidation Reactions
Metadata Field | Value | Language |
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dc.contributor.advisor | Gorden, Anne | |
dc.contributor.author | Black, Clayton | |
dc.date.accessioned | 2020-04-09T18:16:53Z | |
dc.date.available | 2020-04-09T18:16:53Z | |
dc.date.issued | 2020-04-09 | |
dc.identifier.uri | http://hdl.handle.net/10415/7105 | |
dc.description.abstract | C-H oxidation is a powerful tool that has changed the face of synthetic organic chemistry over the last several years. Here, we explore the oxidation of alkynes to α,β-acetylenic carbonyls using only 1 mol % of an inexpensive Cu(II) 2-quinoxalinol salen catalyst with tert-butyl hydroperoxide (TBHP) as the oxidant in 4 hours. These reactions proceed under mild conditions (70 °C) with excellent selectivity, producing yields as high as 78 %. The optimized conditions were used with a variety of alkyne substrates to prepare the desired α,β-acetylenic ketones. Further, we report the ability to do these reactions in aqueous systems using a sulfonated version of the 2-quinoxalinol salen with good yields, thus reducing the need for volatile organic solvents and promoting “green chemistry.” Next, we investigate the use of salen type ligand supports for copper in C-H oxidation catalysis. The oxidation of allylic, propargylic, and benzylic C-H bonds is explored. A series of different ligands were tested in an effort to optimize these C-H oxidations. Derivatives of salen were prepared by altering the aldehyde and diamine starting materials. Upon investigation, the Cu(II) 2-quinoxalinol complex produced the best overall yields. This catalyst can be easily prepared in 5 synthetic steps from abundant starting materials. Finally, oxidative Mannich reactions can be catalyzed using the Cu(II) 2-quinoxalinol salen catalyst and tert-butyl hydroperoxide as the oxidant. Coupling between tertiary amines and carbon-based nucleophiles was found to be highly efficient utilizing this method. Under mild conditions, a range of both cyclic and open chain tertiary amines were investigated as substrates, resulting in yields up to 98 %. A radical reaction mechanism was proposed proceeding through a single electron transfer as the rate determining step. This method provides one alternative to more expensive and/or toxic catalysts. | en_US |
dc.rights | EMBARGO_GLOBAL | en_US |
dc.subject | Chemistry and Biochemistry | en_US |
dc.title | Copper(II) 2-Quinoxalinol Salen Type Ligands as Catalysts for C-H Oxidation Reactions | en_US |
dc.type | PhD Dissertation | en_US |
dc.embargo.length | MONTHS_WITHHELD:24 | en_US |
dc.embargo.status | EMBARGOED | en_US |
dc.embargo.enddate | 2022-04-09 | en_US |
dc.creator.orcid | 0000-0001-9993-0694 | en_US |