Mechanistic Studies of Silsesquioxane Silanol Organocatalysis and Development of Carbene Insertion into Si–H Bonds for Silicon-Stereogenic Silanes and Functionalized Silsesquioxanes
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Mechanistic Studies of Silsesquioxane Silanol Organocatalysis and Development of Carbene Insertion into Si–H Bonds for Silicon-Stereogenic Silanes and Functionalized Silsesquioxanes

Abstract

Organosilicon chemistry is underdeveloped and warrants focus both in synthesis and applications. This dissertation includes a mechanistic analysis of incompletely condensed polyhedral oligomeric silsesquioxane H-bond-donor catalysis in a C–C bond-forming reaction and metal-catalyzed carbene insertion to produce silicon-stereogenic silanes and silsesquioxane nano building blocks. The introduction discusses the properties and applications of silanols, previous methods to access silicon-stereogenic molecules and silsesquioxane-based materials, modern kinetic analysis methods, and carbene insertion into Si–H bonds. Previous literature examples are included for context. Chapter one details a 19F NMR kinetic study of silsesquioxane H-bonding catalysis in a C–C bond-forming reaction using modern kinetic analysis. A comparison of the catalytic activity to previously studied organosilanols is included. The effect of catalyst concentration on the overall mechanism of the transformation is described. Binding studies using 1H NMR spectroscopy were used to investigate H-bonding ability and investigate the effect of concentration. Chapter two presents the development of Rh(II)-catalyzed diarylcarbene insertion into Si–H bonds to produce silicon-stereogenic silanes. Novel prochiral silanes and diazo compounds were synthesized to investigate their effects on enantioselectivity. The effect of a prochiral diazo compound on enantioselectivity was explored. A brief mechanistic study provided insight into structural effects on diazo compound stability. Further transformations of insertion products were explored. Chapter three describes the development of Rh(II)-catalyzed aryl(ester) carbene insertion into Si–H bonds of silsesquioxane-based silanes. Aryl(ester) and aryl(amide) diazo compounds were tested against POSSs with one, three, and eight Si–H bonds. Novel diazo compounds were synthesized containing fluorinated groups and BODIPY fluorophores. Further transformations of insertion products were explored.

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