The Oxidation-Initiated Nazarov Cyclization and Other Pericyclic Transformations

Abstract

The synthesis of interesting and useful cyclic structures is of high importance in chemistry. Strategies for their synthesis include pericyclic reactions, namely electrocyclizations and cycloadditions. This thesis will discuss the investigation towards the synthesis of cyclic structures via Nazarov cyclization, as well as a catalytic thermal [2+2] cycloaddition. Chapter 1 describes recent advances in the Nazarov cyclization. A growing area is the use of non-traditional reagents to activate the divinyl ketone and derivatives towards cyclization. This provides alternative and sometimes milder conditions for the reaction. Another area of interest is the use of non-traditional substrates in the Nazarov cyclization, allowing access to interesting novel products. Chapter 2 describes efforts towards the oxidation-initiated cyclization of non-traditional Nazarov substrates, such as silyl enol ethers and allylic ethers. Interestingly, products of these reactions when using DDQ as the oxidant resulted in DDQ adduct structures, via Diels-Alder reaction. Chapter 3 describes the development of a catalytic Lewis acid mediated formal [2+2] cycloaddition of o-styrenyl chalcones, forming bicyclic structures. A preliminary investigation into an asymmetric transformation is also presented.