Toward an Understanding of Hydrogen-Bonding Bifunctional Organocatalyst Conformations and Their Activity in Asymmetric Mannich Reactions
Small molecule catalysts capable of simultaneously activating and coordinating
reactive substrates through weak interactions, in a highly selective fashion, typically
suffer from a lack of generality. Moreover, the interplay of several weak
interactions in catalyst-substrate complexes is often not well understood. The aim
of this thesis is to explain the factors governing the complexation and the activation
of hydrogen bonding substrates with conformationally flexible bifunctional
thiourea-tertiary amine organocatalysts during the catalytic cycle. Enantioselective
Mannich reactions were used as model reactions. The catalyst family discovered
in a prior study was further screened and developed to improve selectivity,
reactivity and to expand the catalyst utility in related reactions. Computational
and kinetic studies were conducted to establish a model explaining the observed
selectivity and reactivity patterns. Additionally, conformational preference of the
catalyst upon anion binding was studied with an array of anions in the solid state
and in the solution to correlate the anion size and shape with observed catalyst
folding. The thesis is based on three peer-reviewed publications.
Keywords: bifunctional organocatalysis, organic synthesis, anion binding,
hydrogen bonding, kinetic experiments
...
Publisher
Jyväskylän yliopistoISBN
978-951-39-8464-9ISSN Search the Publication Forum
2489-9003Contains publications
- Artikkeli I: Neuvonen, A., & Pihko, P. (2014). Enantioselective Mannich reaction of β-keto esters with aromatic and aliphatic imines using a cooperatively assisted bifunctional catalyst. Organic Letters, 16 (19), 5152-5155. DOI: 10.1021/ol5025025
- Artikkeli II: Neuvonen, A., Földes, T., Madarász, Á., Pápai, I., & Pihko, P. (2017). Organocatalysts Fold to Generate an Active Site Pocket for the Mannich Reaction. ACS Catalysis, 7 (5), 3284-3294. DOI: 10.1021/acscatal.7b00336
- Artikkeli III: Neuvonen, Antti J.; Noutsias, Dimitris; Topić, Filip; Rissanen, Kari; Földes, Tamás; Pápai, Imre; Pihko, Petri M. (2019). Dynamic Refolding of Ion-Pair Catalysts in Response to Different Anions. Journal of Organic Chemistry, 84 (23), 15009-15019. DOI: 10.1021/acs.joc.9b01980
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- JYU Dissertations [775]
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