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The effect of substituents, structure of the reactant and type of active sites on the reaction rate and selectivity of cyclization reactions
Živný, Marek ; Veselý, Ondřej (advisor) ; Bulánek, Roman (referee)
Tetrahydropyrans (THPs) are valuable compounds in the synthesis of pharmaceuticals and fragrances. Currently, THPs are most commonly synthesized using the Prins cyclisation, hetero-Diels-Alder reaction and oxy-Michael reaction. These reactions are undesirable because they use catalysts based on heavy metals and strong acids, which are harmful to the environment. In this thesis, we investigated the synthesis of THPs with the aim of replacing toxic heavy metals and strong acids with more benign catalysts, such as zeolites. Zeolites are microporous crystalline metallosilicates, which are commonly used as catalysts due to their high acidity, selectivity and stability. Previous research has successfully shown that zeolites can catalyse THP synthesis through cyclisation of unsaturated alcohols and determined the effect of pore size on catalytic activity. In contrast, this work aimed to examine zeolites with different framework elements, which introduce diverse types of acid sites. Additionally, we aimed to investigate the impact of functional groups present in the structure of the reactants, specifically functional groups with either electron-donating (EDG) or electron-withdrawing (EWG) effects and with different aromatic cycle systems. We chose (E)5-phenyl-4-pentenol as the primary reactant for the cyclisation....
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