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Photogeneration Mechanism of Reactive Intermediate and its Applications in Photoremovable Protecting Group and Natural Product Synthesis

Das, Anushree
http://orcid.org/0000-0002-6401-9275
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479814832756981

Abstract Details

2017, PhD, University of Cincinnati, Arts and Sciences: Chemistry.
Reactive intermediates play a key role in reaction mechanism. Knowing them enables us to design new organic molecules with distinct applications. We have investigated the following intermediates with respect to their generation process and corresponding reactions using product studies, laser flash photolysis studies, phosphorescence, electron spin resonance spectroscopy, quantum mechanical calculations, molecular dynamics etc. i) Triplet 1,4 Biradicals: They are often generated in ortho alkyl acetophenone systems via. gamma hydrogen atom abstraction by triplet ketones. We have proven that gamma hydrogen abstraction from ortho alkyl is more favorable than side chain, by determining corresponding transition state barrier (chapter 3). ii) Photoenols: Photoenols are singlet species and they are often generated from triplet 1,4 biradicals via. photoenolization process. Photoenols are categorized into Z- and E-enols. Z-enols being short-lived, often undergoes 1,5 H-shift to starting material. We have accounted for electronic and steric influences on corresponding transition state barrier (chapter 2 and 4). E-enols are responsible for product formation. Depending on transition state barrier, they undergo photolactonization process to release protecting group (chapter 3 and 4). This feature of E-enol enables us to design new photoremovable protecting group (PRPG). Few E-enols are flexible enough to undergo bond rotation, followed by electrocyclic ring closure to product natural products with efficient yield (chapter 5). iii) Triplet nitrene: Nitrenes are generated via. release of nitrogen from precursor azide. We have studied the photochemistry of corannulene azide, which upon irradiation generates triplet corannulene nitrene. Due to curvature of corannulene, triplet corannulene nitrene is vinylic in nature, which is established from electron spin resonance (ESR) spectroscopy and spin calculations. Corannulene nitrene possesses triplet 1,3 biradical character with electron densities on nitrogen and vinylic carbon atoms (chapter 6).
Anna Gudmundsdottir, Ph.D. (Committee Chair)
Bruce Ault, Ph.D. (Committee Member)
James Mack, Ph.D. (Committee Member)
178 p.
Organic Chemistry

Recommended Citations

Citations

  • Das, A. (2017). Photogeneration Mechanism of Reactive Intermediate and its Applications in Photoremovable Protecting Group and Natural Product Synthesis [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479814832756981

    APA Style (7th edition)

  • Das, Anushree. Photogeneration Mechanism of Reactive Intermediate and its Applications in Photoremovable Protecting Group and Natural Product Synthesis. 2017. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479814832756981.

    MLA Style (8th edition)

  • Das, Anushree. "Photogeneration Mechanism of Reactive Intermediate and its Applications in Photoremovable Protecting Group and Natural Product Synthesis." Doctoral dissertation, University of Cincinnati, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479814832756981

    Chicago Manual of Style (17th edition)

ucin1479814832756981
179
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This open access ETD is published by University of Cincinnati and OhioLINK.