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Environmentally Benign Method Development Towards the Synthesis of Oxygen-Containing Heterocycles

Lawrence, Jean-Marc Irvin Anthony (2022) Environmentally Benign Method Development Towards the Synthesis of Oxygen-Containing Heterocycles. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Abstract

Oxygen-containing heterocycles are highly diverse and attractive targets in chemical synthesis that are prevalent in many biologically active natural products. Synthesizing these structures in an environmentally friendly manner can increase the use of these methods and their applicability in industry and medicinal chemistry. This document describes a dehydrative Re2O7-catalyzed approach in the activation of 1,3- and 1,5-monoallylic diols, which generate an allylic cation intermediate that is captured by a pendent alcohol to synthesize 3,4-dihydropyrans. The 2,6-trans-isomer was determined to be the kinetic and thermodynamically favored isomer. A substrate scope is developed to determine the functional group tolerance, and stereocontrol is enhanced through the incorporation of a pendent stereocenter on the dihydropyran ring. Furthermore, an investigation of the mechanism is shown through the manipulation of alkene geometry and stereochemistry to discover a unique SNi mechanism.
Electrochemical oxidative C−H functionalization is an advantageous way of increasing molecular complexity with high functional group tolerance while minimizing cost and waste. Kinetically slow oxidations followed by C−C and C−O bond formation present challenges in the effective turnover of catalytic oxidants under anhydrous conditions due to low steady-state concentrations of reduced oxidant. TEMPO-based oxoammonium salts are effective hydride abstracting reagents in the oxidation of ethers, amines, and carbamates to generate excellent electrophiles. Results described herein show that intermediate cation stability, oxidant strength, overpotential, and concentration dictate the rate of electrochemical regeneration of oxoammonium salts in the oxidation of benzylic and allylic ethers. Integrating these factors leads to a new method that synthesizes a diverse substrate scope of oxygen and nitrogen-containing heterocycles, changing the approach toward kinetically slow oxidations in future electrochemical methods.


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Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Lawrence, Jean-Marc Irvin Anthonyjel190@pitt.edujel190
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairFloreancig, Paulflorean@pitt.edu
Committee MemberDeiters, Alexanderdeiters@pitt.edu
Committee MemberWang, Yimingym.wang@pitt.edu
Committee MemberMcKone, Jamesjmckone@pitt.edu
Date: 12 October 2022
Date Type: Publication
Defense Date: 28 June 2022
Approval Date: 12 October 2022
Submission Date: 12 July 2022
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 302
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Alcohols, Cations, Cyclization, Electrochemistry, Catalysis, Oxidation, C-H Functionalization
Date Deposited: 12 Oct 2022 14:58
Last Modified: 12 Oct 2022 14:58
URI: http://d-scholarship.pitt.edu/id/eprint/43325

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  • Environmentally Benign Method Development Towards the Synthesis of Oxygen-Containing Heterocycles. (deposited 12 Oct 2022 14:58) [Currently Displayed]

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