Controlled Access. Restriction lift date: 2031-06-30
Studies in manganese-catalysis in C ̶H activation and reductive transformations
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Date
2025-12-31
Authors
Ko, Si Lok
Journal Title
Journal ISSN
Volume Title
Publisher
University College Cork
Published Version
Abstract
In recent years, earth-abundant 3d transition-metal catalysts, such as those involving manganese, have gained popularity as alternatives to expensive precious metal based systems. This trend stems from the urgent need to develop new, efficient, and sustainable green methodologies. The use of readily available metals, instead of noble metals, is a key focus in green chemistry.
Chapter 2 showcases a robust methodology involving Mn catalysed C−H allylation at the C2 position of 1-(pyridin-2-yl)-1H-indole in water. The efficient and selective derivatisation of heteroarenes is a critical tool in organic synthesis. Due to its unique ability to functionalise at the C2 position of indole, the less nucleophilic position in the pyrrolic ring of indole, it is a highly desirable method. This protocol has demonstrated very good applicability, including the functionalisation of medicinally relevant melatonin and site-selective deuterium incorporation.
Chapter 3 highlights the preparation of various Mn-complexes. The Mn-complexes prepared were used in an attempt catalyse the deuteration of 1-(pyridin-2-yl)-1H-indole, and ρ-anisaldehyde via an imine transient directing group (TDG) using a cheap deuterium source, D2O. This is a highly attractive method for various applications involving deuterium. Site specific deuteration is a highly desirable method, particularly if it does not require elaborate procedures or toxic metals. An investigation into manganese-catalysed imine TDG-assisted ortho-C−H functionalisation of benzaldehyde for C−C bond formation is also discussed.
Chapter 4 explores a heterogeneous manganese-catalysed reduction of esters and aldehydes. Given the nature of many reducing agents and methodologies involving hydrogen gas, a safe, efficient, and facile method is beneficial. This protocol displays good versatility with some functional group tolerance, “recyclability” of the catalyst, and was also applied in flow chemistry. The heterogeneous catalyst was studied to investigate the true nature of this catalyst.
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Controlled Access
Keywords
Manganese , Catalysis , Deuteration , C−H activation , C−H functionalisation , Heterogenous catalysis , Indole , MnBr(CO)5 , Flow chemistry
Citation
Ko, S. L. 2025. Studies in manganese-catalysis in C ̶H activation and reductive transformations. PhD Thesis, University College Cork.