Applications of homogeneous and heterogeneous photocatalysts for late-stage transformations of organic molecules
The employment of costly, single-use catalysts, and additionally, highly toxic reagents/reactants, and solvents is still a major concern in synthetic organic chemistry. Therefore, it becomes difficult for pharma industries to reduce the price as well as environmental toxicity. In this regard, ample attention needs to be considered by the chemical community to replace them with inexpensive, abundant, benign, and reusable substitutes. The goal of my doctoral thesis was to contribute towards the sustainable development of novel synthetic methodologies for the synthesis and late-stage functionalizations of pharmaceutical molecules and natural products by using metal-free homogeneous photocatalysts followed by single metal atom photocatalysts. The research described in this thesis can be divided into two major parts: in the first part, two different methodologies have been developed for the formation of aminated products by using different homogeneous organo-photocatalysts. The first one comprises regioselective functionalizations of benzylic C(sp3)–H bonds by using a mesityl acridinium photocatalyst in the presence of different amine nucleophiles. Interestingly, this system also enabled ethers and ester products when alcohols and acids were considered as nucleophiles. The second one involved the production of functionalized linear aliphatic amines via hydroaminoalkylations by using 4CzIPN as a photocatalyst. In the second part, two different single metal atom photocatalysts supported by modified g-C3N4 have been used for the dichlorination of alkenes and furthermore, selective para-chlorination of electron-rich (hetero)arenes. The thesis work is presented in five chapters and results are graphically summarized underneath: Chapter 1 provides an overview of the basic concepts of visible-light-mediated chemical processes that prevail in organic synthesis by using both homogeneous and heterogeneous photocatalysts. Chapter 2 describes the development of a robust, cost and energy-efficient strategy to introduce diverse nucleophiles including alcohols, carboxylic acids, and amines via the functionalization of benzylic C−H bonds as well as complex drug molecules and natural products. Chapter 3 demonstrates a redox-neutral decarboxylative radical polar crossover process for the synthesis of linear aliphatic amines by using 4CzIPN as an organophotocatalyst. The synthetic utility of this method is further demonstrated by the late-stage functionalizations of pharmaceuticals as well as in the synthesis of drug compounds. Chapter 4 describes an Mn-based single-metal atom photocatalyst that has been developed to achieve the vicinal dichlorination of alkenes by using N-chlorosuccinamide as a chlorinating agent. Noteworthily, both the unactivated and activated alkenes provided good to excellent yield under the mild reaction conditions. Interestingly, 8 pharmaceutical compounds have been functionalized with our system to prove the synthetic applicability of our method. Finally, Chapter 5 demonstrates a Mn-based single metal atom photocatalytic method for the selective para-chlorination of aromatics by using N-chlorosuccinamide as a chlorinating agent. Mostly electron-rich aromatics worked in this system.
Antwerpen : Universiteit Antwerpen, Faculteit Wetenschappen, Departement Chemie , 2023
vii, 217
Supervisor: Das, Shoubhik [Supervisor]
Supervisor: Maes, Bert U.W. [Supervisor]
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The publisher created published version Available from 02.10.2025
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Creation 28.09.2023
Last edited 04.10.2023
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