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Photoredox Strategies for Asymmetric Catalysis and Determination of Open-Shell Hammett Substituent Constants
Photoredox Strategies for Asymmetric Catalysis and Determination of Open-Shell Hammett Substituent Constants
상세정보
- 자료유형
- 학위논문 서양
- 최종처리일시
- 20260202104828
- ISBN
- 9798297600102
- DDC
- 547
- 저자명
- Xu, Eve Yuanwei.
- 서명/저자
- Photoredox Strategies for Asymmetric Catalysis and Determination of Open-Shell Hammett Substituent Constants
- 발행사항
- [Sl] : Princeton University, 2025
- 발행사항
- Ann Arbor : ProQuest Dissertations & Theses, 2025
- 형태사항
- 442 p
- 주기사항
- Source: Dissertations Abstracts International, Volume: 87-04, Section: B.
- 주기사항
- Advisor: Knowles, Robert R.
- 학위논문주기
- Thesis (Ph.D.)--Princeton University, 2025.
- 초록/해제
- 요약Free radicals are typically viewed as transient and highly reactive species. Precise modulation of their reactivity continues to be a fundamental challenge in organic synthesis. Meanwhile, advancements in photoredox catalysis have enabled the efficient and selective generation of a wide range of radical intermediates, broadening their utility in synthetic methodologies. This dissertation broadly examines the reactivity and properties of organic radicals, focusing particularly on species formed under photoredox conditions.Chapter 1 presents a detailed mechanistic study of enantioselective hydroamination of alkenes with sulfonamides enabled by proton-coupled electron transfer (PCET). The study suggests that the basis for asymmetric induction arises from attractive noncovalent interactions within a post-PCET H-bonding complex formed between a neutral sulfonamidyl radical intermediate and a chiral phosphoric acid catalyst.Chapter 2 describes the development of a light-driven method for enantioselective contrathermodynamic olefin isomerization. Sequential oxidation and deprotonation of a tetra-substituted enol ether produces an allyl radical, which is captured by a Cr(II) cocatalyst bearing a chiral bi-oxazoline (BiOX) ligand. Subsequent regio- and enantioselective protodemetalation of the resulting Cr(III) allyl complex by methanol affords the enantioenriched terminal olefin product, achieving selectivity up to 95:5 er.Chapter 3 outlines a combined experimental and computational approach to determine Hammett constants for open-shell substituents, based on changes in nitrile vibrational frequencies (ν(C≡N)). By coupling pulse radiolysis with time-resolved infrared spectroscopy (PR-TRIR), ν(C≡N) IR bands were measured for 30 para- and meta-substituted benzonitriles bearing C-, N-, and S-centered radicals. A linear scaling relationship was established between the experimental data and values obtained from DFT calculations. Using computed values, two distinct Hammett constants, σm and σp+, were derived for a series of C-, N-, O-, S-, Si-, and B-centered radicals.
- 일반주제명
- Organic chemistry
- 일반주제명
- Physical chemistry
- 일반주제명
- Analytical chemistry
- 키워드
- Radicals
- 키워드
- Olefins
- 기타저자
- Princeton University Chemistry
- 기본자료저록
- Dissertations Abstracts International. 87-04B.
- 전자적 위치 및 접속
- 로그인 후 원문을 볼 수 있습니다.
MARC
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■020 ▼a9798297600102
■035 ▼a(MiAaPQ)AAI32170154
■040 ▼aMiAaPQ▼cMiAaPQ
■0820 ▼a547
■1001 ▼aXu, Eve Yuanwei.▼0(orcid)0000-0002-7212-3363
■24510▼aPhotoredox Strategies for Asymmetric Catalysis and Determination of Open-Shell Hammett Substituent Constants
■260 ▼a[Sl]▼bPrinceton University▼c2025
■260 1▼aAnn Arbor▼bProQuest Dissertations & Theses▼c2025
■300 ▼a442 p
■500 ▼aSource: Dissertations Abstracts International, Volume: 87-04, Section: B.
■500 ▼aAdvisor: Knowles, Robert R.
■5021 ▼aThesis (Ph.D.)--Princeton University, 2025.
■520 ▼aFree radicals are typically viewed as transient and highly reactive species. Precise modulation of their reactivity continues to be a fundamental challenge in organic synthesis. Meanwhile, advancements in photoredox catalysis have enabled the efficient and selective generation of a wide range of radical intermediates, broadening their utility in synthetic methodologies. This dissertation broadly examines the reactivity and properties of organic radicals, focusing particularly on species formed under photoredox conditions.Chapter 1 presents a detailed mechanistic study of enantioselective hydroamination of alkenes with sulfonamides enabled by proton-coupled electron transfer (PCET). The study suggests that the basis for asymmetric induction arises from attractive noncovalent interactions within a post-PCET H-bonding complex formed between a neutral sulfonamidyl radical intermediate and a chiral phosphoric acid catalyst.Chapter 2 describes the development of a light-driven method for enantioselective contrathermodynamic olefin isomerization. Sequential oxidation and deprotonation of a tetra-substituted enol ether produces an allyl radical, which is captured by a Cr(II) cocatalyst bearing a chiral bi-oxazoline (BiOX) ligand. Subsequent regio- and enantioselective protodemetalation of the resulting Cr(III) allyl complex by methanol affords the enantioenriched terminal olefin product, achieving selectivity up to 95:5 er.Chapter 3 outlines a combined experimental and computational approach to determine Hammett constants for open-shell substituents, based on changes in nitrile vibrational frequencies (ν(C≡N)). By coupling pulse radiolysis with time-resolved infrared spectroscopy (PR-TRIR), ν(C≡N) IR bands were measured for 30 para- and meta-substituted benzonitriles bearing C-, N-, and S-centered radicals. A linear scaling relationship was established between the experimental data and values obtained from DFT calculations. Using computed values, two distinct Hammett constants, σm and σp+, were derived for a series of C-, N-, O-, S-, Si-, and B-centered radicals.
■590 ▼aSchool code: 0181.
■650 4▼aOrganic chemistry
■650 4▼aPhysical chemistry
■650 4▼aAnalytical chemistry
■653 ▼aAsymmetric catalysis
■653 ▼aHammett constants
■653 ▼aPhotoredox catalysis
■653 ▼aRadicals
■653 ▼aOlefins
■690 ▼a0490
■690 ▼a0486
■690 ▼a0494
■71020▼aPrinceton University▼bChemistry.
■7730 ▼tDissertations Abstracts International▼g87-04B.
■790 ▼a0181
■791 ▼aPh.D.
■792 ▼a2025
■793 ▼aEnglish
■85640▼uhttp://www.riss.kr/pdu/ddodLink.do?id=T17359056▼nKERIS▼z이 자료의 원문은 한국교육학술정보원에서 제공합니다.
