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|Title:||Carbene-catalyzed dynamic kinetic resolutions and cycloaddition reactions via acylazolium intermediates||Authors:||Song, Runjiang||Keywords:||Science::Chemistry||Issue Date:||2022||Publisher:||Nanyang Technological University||Source:||Song, R. (2022). Carbene-catalyzed dynamic kinetic resolutions and cycloaddition reactions via acylazolium intermediates. Doctoral thesis, Nanyang Technological University, Singapore. https://hdl.handle.net/10356/154700||Abstract:||This thesis focuses on exploring the reactivity of N-heterocyclic carbene (NHC) catalyst-derived acylazolium intermediates. In particular, the thesis is mainly focused on NHC-catalyzed dynamic kinetic resolution (DKR) and cycloaddition reactions through formation of acylazolium intermediates. It contains three chapters: Chapter 1 provides a brief review on the history and development of NHCs in organic catalysis. A number of classical reactive intermediates and key reaction modes in NHC catalysis are summarized. Literature studies closely related to the thesis work are introduced. Chapter 2 describes an NHC-catalyzed DKR and transesterification reaction for asymmetric synthesis of optically enriched α-aryloxycarboxylic esters with up to 99% yield and 99:1 er value. The facile interconversion between two NHC-activated diastereomeric acylazolium intermediates allows for highly efficient DKR to occur. The products from our strategy can readily undergo further transformations to produce chiral herbicides and other functional molecules. Chapter 3 presents a highly chemo- and enantioselective organocatalytic tandem reaction between hydroxylamines and bromoenals. The reaction provides access to isoxazolidin-5-ones in good yields and satisfactory enantioselectivities. Chapter 4 provides the conclusion and perspective of this thesis, including potential scientific and real-world applications derived from our study.||URI:||https://hdl.handle.net/10356/154700||DOI:||10.32657/10356/154700||Rights:||This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).||Fulltext Permission:||open||Fulltext Availability:||With Fulltext|
|Appears in Collections:||SPMS Theses|
Updated on Feb 5, 2023
Updated on Feb 5, 2023
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