Browsing by Author "Säde, Solja"

Photocatalytic reactions utilize energy harnessed from light for the activation of a catalyst. In photoredox catalysis, an excited photocatalyst can take part in redox reactions with a substrate. The most common photocatalysts could be divided into three classes: metal catalysts, organic dyes, and heterogeneous semiconductors. These catalysts are often employed with a transition metal dual catalyst. The dual catalyst enables the cross-coupling of substrates, and the photocatalyst oxidizes or reduces the dual catalyst. Photocatalytic reactions can offer a milder alternative for the traditional C-N coupling reactions. In the literature review section, the photocatalytic N-arylation of pyrrolidines was examined. The review found that pyrrolidines were successfully N-arylated with all of the catalyst types, and multiple variations on the substituents on the aryl halide. In the majority of the research, electron withdrawing groups (EWG) as substituents enhanced product yields, but electron donating groups (EDG) decreased yields. In an organic dye catalysed reaction, the effects of the substituents were opposite. In addition, the photocatalytic reactions were compared with traditional C-N coupling reactions, such as the Buchwald-Hartwig reaction, Ullmann-type reactions nucleophilic aromatic substitution and the Chan-Lam reaction. These reactions often had harsh reaction conditions. The photocatalytic N-arylation of 3-substituted pyrrolidines was examined in the experimental part of this thesis. The objectives of this study were to investigate the use of photoredox methodologies for the C-N coupling of 3-substituted pyrrolidines to arenes and examine the scope and limitations of the reaction and the effects of substituents. In addition, the aim was to optimize the reaction conditions for multiple parameters and for each product separately, apply the reaction on a flow chemistry appliance, and execute scale-up reactions on both photoreactors. The study found 3-substituted pyrrolidines to be successfully coupled with aryl halides with great variation in the substituents of both starting materials. With optimization, the reactions with lower product yields were able to be improved significantly. The reaction was successfully upscaled, but the adaptation on the flow reactor requires further optimization. Photocatalytic C-N coupling reactions offer a promising alternative for traditional reactions.