Download or read book Design, Synthesis, and Investigation of Siloxanol Hydrogen-bonding Catalysts and Chiral Silanol Ligands written by Kayla Marie Diemoz and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The synthesis and study of organosilanols can lead to the development of effective hydrogen-bonding catalysts and chiral ligands for Lewis acid catalysis. This dissertation discusses the development of 1,3-disiloxanediols and incompletely condensed polyhedral oligomeric silsesquioxanes as novel hydrogen-bonding catalysts, with insight into hydrogen-bonding properties. Chiral silanol-containing ligands have also been developed with applications in Lewis acid catalysis. Mechanistic studies to better understand how silanol-containing catalysts activate substrates will also be presented. The introduction discusses relevant silicon chemistry including the unique properties of silicon that are utilized to make effective catalysts. Previous literature in the areas of silanol hydrogen-bonding catalysts and silanol-containing ligands for metal-catalysis is highlighted. The importance of mechanistic studies to learn about the activation mode of organocatalysts is emphasized with recent literature examples. Chapter one describes the synthesis and investigation of the hydrogen-bonding ability of 1,3-disiloxanediols. The synthetic route to access novel disiloxanediol structures with a variety of steric and electronic effects is presented. 1H NMR spectroscopy binding studies with both anionic and neutral Lewis basic binding partners were conducted to examine hydrogen-bonding properties. Diffusion-ordered spectroscopy studies were used to assess self-association of disiloxanediols in solution and demonstrate that concentration dependent self-association is observed. Chapter two outlines the use of 1,3-disiloxanediols as effective hydrogen-bonding and anion-binding organocatalysts. The catalytic activity of 1,3-disiloxanediols is compared to other silanol catalysts to understand the features of 1,3-disiloxanediols that enhance their catalytic ability relative to silanol catalysts. I describe an in-depth kinetic study that was performed for the indole addition to nitrostyrene catalyzed by a 1,3-disiloxanediol catalyst to elucidate information about the mode of activation of 1,3-disiloxanediols. Chapter three describes the use of 31P NMR spectroscopy to evaluate and quantify the hydrogen-bond activation for a wide variety of organocatalysts including phenols, benzoic acids, silanol-containing compounds and boronic acids. Hydrogen-bond donors with a variety of steric and electronic effects were utilized to understand factors that contribute to hydrogen-bond activation. The measured hydrogen-bond activation was compared to relative rate in a Friedel-Crafts reaction and the 31P NMR probe was found to be an excellent predictor of reactivity; especially when compared to traditional metrics including pK[subscript a]. Chapter four discusses the use of incompletely condensed polyhedral oligomeric silsesquioxanes (POSS-silanols) as hydrogen-bonding catalysts. Hydrogen-bonding properties of POSS-silanols were investigated using both 1H and 31P NMR binding studies. A kinetic study was performed on the indole addition to nitrostyrene catalyzed by POSS-silanols where an intriguing concentration effect was observed, and indicated a change in reaction mechanism depending on the POSS-silanol concentration. Chapter five presents the synthesis and investigation of silanol-containing chelating ligands with applications in asymmetric catalysis. A modular synthetic route that allows for steric and electronic modifications has been developed to access various silanol-oxazoline (SiOX) ligands. Mass spectrometry and 1H NMR binding studies were used to identify metals that should be investigated for catalytic activity with SiOX ligands. Preliminary enantioselectivity in a [3 +2] silver-catalyzed intramolecular cycloaddition reaction is also discussed.