Development and optimization of photoredox-mediated methine epimerization
Name
wang-kath1een-ms-chemistry-2021-thesis.pdf
Description
Thesis PDF
Size
1.4 MB
Format
Adobe PDF
Checksum (MD5)
122a3191048baca1ef540bd766918b83
Author(s)
Wang, Kathleen J
Advisor(s)
Wendlandt, Alison E
Date Issued
June 2021
Publisher
Massachusetts Institute of Technology
Abstract
Reactions that edit the stereochemistry of individual atoms are enabling tools in synthetic chemistry. The Wendlandt lab has developed a sequential H-atom abstraction and donation strategy to synthesize rare sugars from biomass platform molecules such as D-glucose. Efforts to apply this strategy to the epimerization of steroids gave poor results and demonstrated limited selectivity, but insights gained from this work were used to develop a hypothesis for epimerization. We proposed that H-atom abstraction and donation occur to release diaxial strain and form the most conformationally stable isomer. This hypothesis guided the development of an epimerization method for methine stereocenters. This work describes the optimization and development of methine epimerization of isomenthyl acetate. The epimerization of tertiary alkyl stereocenters is also applied to access an otherwise synthetically challenging stereochemical outcome from a Diels-Alder reaction sequence. Data from primary literature and mechanistic experiments are used to provide a proposed mechanism through which this epimerization proceeds.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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