Formation of (hetero)cyclic molecules via the electrocyclizatin of keteniminium intermediates

Keteniminium intermediates which can also be called keteniminium salts due to their catrionic nature are important building blocks in organic synthesis. Easy access to KIs as well as easy storage and their unique structure leading to versatility have made them preferred over ketenes in time. On the other hand, electrocyclization is a powerful method for obtaining complex biological structures. Products of keteniminium electrocyclizations can be used in pharmaceuticals, agrochemicals, fluorescent chemosensors, which is used in various disciplines such as biology and environmental sciences, and several others. This thesis focuses on the electrocyclization of keteniminium salts from a computational perspective. First of all, the mechanism of keteniminium cyclization was uncovered by means of DFT analysis. Then, the effect of several substituents and heteroatoms in the cyclic structure on the reactivity were evaluated and compared energetically. After single electrocyclizations, the ease of consecutive double electrocyclizations were investigated. Furthermore, the nature of the electrocyclization reaction was revealed by using a variety of analysis techniques. The connection between the aromatic character of the keteniminium molecule by means of number of aromatic rings it possesses, and the ease of electrocyclization was studied. This thesis was intended to provide insight into the keteniminium electrocyclization mechanism and the reactivity differences between different KIs for the purpose of aiding further research and application in distinctive scientific and technological developments.