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Expanding the Utility of Configurationally Unstable Compounds: Generating Molecular Complexity Through Organocatalyzed, Stereoconvergent Processes
Expanding the Utility of Configurationally Unstable Compounds: Generating Molecular Complexity Through Organocatalyzed, Stereoconvergent Processes
상세정보
- 자료유형
- 학위논문 서양
- 최종처리일시
- 20260202104806
- ISBN
- 9798291558669
- DDC
- 547
- 서명/저자
- Expanding the Utility of Configurationally Unstable Compounds: Generating Molecular Complexity Through Organocatalyzed, Stereoconvergent Processes
- 발행사항
- [Sl] : The University of North Carolina at Chapel Hill, 2025
- 발행사항
- Ann Arbor : ProQuest Dissertations & Theses, 2025
- 형태사항
- 357 p
- 주기사항
- Source: Dissertations Abstracts International, Volume: 87-02, Section: B.
- 주기사항
- Advisor: Johnson, Jeffrey S.
- 학위논문주기
- Thesis (Ph.D.)--The University of North Carolina at Chapel Hill, 2025.
- 초록/해제
- 요약I. Catalytic, Asymmetric Michael-Aldol Annulations via a Stereodivergent/Stereoconvergent Path Operating Under Curtin-Hammett ControlA bifunctional iminophosphorane (BIMP)-catalyzed method for the synthesis of densely functionalized cyclohexanols establishes five contiguous stereocenters (diastereoselection up to 20:1, enantioselectivity up to 99:1) in a Michael/aldol domino reaction between trisubstituted electrophilic alkenes and γ-nitro ketones. Mechanistic studies suggest a scenario in which stereoconvergency is achieved by kinetically controlled cyclization after the initial diastereodivergent Michael addition. Diastereoconvergency during cyclization is shown to result from Curtin-Hammett kinetics, a finding that contrasts the crystallization-driven stereoconvergency previously reported in similar systems. Despite the change in stereocontrol mechanism, the operational attributes remain attractive, with the crystalline products typically isolated in analytically pure form upon filtration of the reaction mixtureII. Diastereoselective (3+3)-Annulations of Trisubstituted Michael Acceptors for Access to Polyfunctional CyclohexanonesMichael-aldol domino reactions are powerful tools for rapidly assembling carbocyclic scaffolds. We herein disclose a base-catalyzed Michael-aldol domino reaction of trisubstituted Michael acceptors with β-keto ester nucleophiles. The cyclohexanone products are obtained in excellent diastereoselectivity (up to 20:1 dr) and good yields (up to 84%). An attractive practical consideration is that pure products are isolated directly via filtration of the unpurified reaction mixtures. Further functionalization of the cyclohexanones is achieved without perturbation of stereocenters installed through the preceding annulation. III. Exploration of a Stereoconvergent Pathway for the Asymmetric, Alkylation of β-keto Esters Employing Chiral, Racemic α-halo EstersEfforts towards the dynamic kinetic resolution of chiral-racemic α-bromo esters are reported. Initial mechanistic information obtained through key experiments suggests the possibility of DKR proving operative through a base mediated racemization pathway. Screening a variety of cinchona alkaloid salts has afforded a current maximum enantiomeric ratio of 75:25. Extensive efforts to optimize reaction variables to increase enantioselectivity are described.IV. A Crystallization Driven Diastereoconvergent Synthesis of Azaarene-Containing TriarylethanesAccess to azaarene-containing triarylethanes is achieved via DBU catalyzed 1,6-conjugate addition of 4-pyridyl acetates or 4-pyridylmethyl ketones into para-quinone methides. Mechanistic studies suggest that crystallization thermodynamics are the sole driving force for the high diastereopurity in the products. This report aims to provide a paradigm to which further exploitation of pyridyl-containing compounds under CIDT manifolds can be recognized. The azaarene-containing products, isolated via vacuum filtration, are valuable, sp3 -rich building blocks for further synthetic derivatization.
- 일반주제명
- Organic chemistry
- 일반주제명
- Chemistry
- 일반주제명
- Molecular chemistry
- 키워드
- Organocatalysis
- 기타저자
- The University of North Carolina at Chapel Hill Chemistry
- 기본자료저록
- Dissertations Abstracts International. 87-02B.
- 전자적 위치 및 접속
- 로그인 후 원문을 볼 수 있습니다.
MARC
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■00520260202104806
■006m o d
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■020 ▼a9798291558669
■035 ▼a(MiAaPQ)AAI32165637
■040 ▼aMiAaPQ▼cMiAaPQ
■0820 ▼a547
■1001 ▼aGiordano, Mitchell Thomas.
■24510▼aExpanding the Utility of Configurationally Unstable Compounds: Generating Molecular Complexity Through Organocatalyzed, Stereoconvergent Processes
■260 ▼a[Sl]▼bThe University of North Carolina at Chapel Hill▼c2025
■260 1▼aAnn Arbor▼bProQuest Dissertations & Theses▼c2025
■300 ▼a357 p
■500 ▼aSource: Dissertations Abstracts International, Volume: 87-02, Section: B.
■500 ▼aAdvisor: Johnson, Jeffrey S.
■5021 ▼aThesis (Ph.D.)--The University of North Carolina at Chapel Hill, 2025.
■520 ▼aI. Catalytic, Asymmetric Michael-Aldol Annulations via a Stereodivergent/Stereoconvergent Path Operating Under Curtin-Hammett ControlA bifunctional iminophosphorane (BIMP)-catalyzed method for the synthesis of densely functionalized cyclohexanols establishes five contiguous stereocenters (diastereoselection up to 20:1, enantioselectivity up to 99:1) in a Michael/aldol domino reaction between trisubstituted electrophilic alkenes and γ-nitro ketones. Mechanistic studies suggest a scenario in which stereoconvergency is achieved by kinetically controlled cyclization after the initial diastereodivergent Michael addition. Diastereoconvergency during cyclization is shown to result from Curtin-Hammett kinetics, a finding that contrasts the crystallization-driven stereoconvergency previously reported in similar systems. Despite the change in stereocontrol mechanism, the operational attributes remain attractive, with the crystalline products typically isolated in analytically pure form upon filtration of the reaction mixtureII. Diastereoselective (3+3)-Annulations of Trisubstituted Michael Acceptors for Access to Polyfunctional CyclohexanonesMichael-aldol domino reactions are powerful tools for rapidly assembling carbocyclic scaffolds. We herein disclose a base-catalyzed Michael-aldol domino reaction of trisubstituted Michael acceptors with β-keto ester nucleophiles. The cyclohexanone products are obtained in excellent diastereoselectivity (up to 20:1 dr) and good yields (up to 84%). An attractive practical consideration is that pure products are isolated directly via filtration of the unpurified reaction mixtures. Further functionalization of the cyclohexanones is achieved without perturbation of stereocenters installed through the preceding annulation. III. Exploration of a Stereoconvergent Pathway for the Asymmetric, Alkylation of β-keto Esters Employing Chiral, Racemic α-halo EstersEfforts towards the dynamic kinetic resolution of chiral-racemic α-bromo esters are reported. Initial mechanistic information obtained through key experiments suggests the possibility of DKR proving operative through a base mediated racemization pathway. Screening a variety of cinchona alkaloid salts has afforded a current maximum enantiomeric ratio of 75:25. Extensive efforts to optimize reaction variables to increase enantioselectivity are described.IV. A Crystallization Driven Diastereoconvergent Synthesis of Azaarene-Containing TriarylethanesAccess to azaarene-containing triarylethanes is achieved via DBU catalyzed 1,6-conjugate addition of 4-pyridyl acetates or 4-pyridylmethyl ketones into para-quinone methides. Mechanistic studies suggest that crystallization thermodynamics are the sole driving force for the high diastereopurity in the products. This report aims to provide a paradigm to which further exploitation of pyridyl-containing compounds under CIDT manifolds can be recognized. The azaarene-containing products, isolated via vacuum filtration, are valuable, sp3 -rich building blocks for further synthetic derivatization.
■590 ▼aSchool code: 0153.
■650 4▼aOrganic chemistry
■650 4▼aChemistry
■650 4▼aMolecular chemistry
■653 ▼aAsymmetric catalysis
■653 ▼aCrystallization induced diastereomer transformations
■653 ▼aOrganocatalysis
■653 ▼aStereochemical complexity
■653 ▼aStereoconvergence
■690 ▼a0490
■690 ▼a0431
■690 ▼a0485
■71020▼aThe University of North Carolina at Chapel Hill▼bChemistry.
■7730 ▼tDissertations Abstracts International▼g87-02B.
■790 ▼a0153
■791 ▼aPh.D.
■792 ▼a2025
■793 ▼aEnglish
■85640▼uhttp://www.riss.kr/pdu/ddodLink.do?id=T17358890▼nKERIS▼z이 자료의 원문은 한국교육학술정보원에서 제공합니다.
