Elimination reactions using aryl isothiocyanates ; intramolecular friedel–crafts cyclizations of arylsilanes
Thompson, Stephen Bradford
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Chapter I: The Chugaev elimination is a commonly-employed method for the preparation of alkenes from alcohols possessing a syn-β-hydrogen. The introduction of tin and silicon atoms as the S substituent of the xanthate instead made it more stable toward pyrolysis, causing it to eliminate at higher temperatures. However, carbonimidothioates, prepared via aryl isothiocyanates, proved to be a viable alternative to the Chugaev elimination, undergoing pyrolysis at the same temperature as S-methyl xanthates. Chapter II: Lewis acid-catalyzed cyclialkylation is an established method for creating tricyclic compounds composed of a central cycloheptane ring. By applying this method to arene-dienone systems with silyl-substituted arenes, we hoped to observe meta-directed electrophilic aromatic substitution with retention of the silyl moiety. Preliminary investigations have proven the silyl moiety too labile, and cyclialkylation was accompanied by protodesilylation.