Enamines as Versatile Synthons for the Electro-oxidative Synthesis of Diverse Heterocycles

Baidya, Mrinmay (2024) Enamines as Versatile Synthons for the Electro-oxidative Synthesis of Diverse Heterocycles. PhD thesis, Indian Institute of Science Education and Research Kolkata.

Text (PhD thesis of Mrinmay Baidya (18RS078)) 18RS078.pdf - Submitted Version Restricted to Repository staff only Download (37MB)

Abstract

The contents within this thesis entitled “Enamines as Versatile Synthons for the Electro-oxidative Synthesis of Diverse Heterocycles” has been organized into eight chapters, reflecting the findings derived from the experimental investigations conducted throughout the entire duration of my research period. In recent years, Electrochemical organic synthesis, a cutting-edge field at the intersection of organic chemistry and electrochemistry, has emerged as a powerful and sustainable method for the construction of complex organic molecules. By harnessing the potential of electricity to drive chemical reactions, researchers are revolutionizing traditional synthetic methodologies. One of the main advantages of electroorganic synthesis is its ability to access unconventional reaction pathways that may be challenging or impossible using traditional methods. The use of electricity allows for precise control over reaction conditions, leading to increased selectivity and efficiency in the formation of target compounds. The technique excels in the construction of complex and structurally diverse molecules allowing the efficient formation of bonds that are difficult to achieve through traditional synthetic routes, making it a valuable tool in medicinal chemistry, materials science, and other interdisciplinary fields. While electroorganic synthesis has made significant strides, challenges remain. The scalability of electrochemical processes, the development of cost-effective catalysts, and the optimization of reaction conditions are areas of ongoing research. Additionally, further integration of computational methods for predicting and optimizing electroorganic reactions is anticipated to enhance efficiency. The future of electroorganic synthesis holds promise in addressing the growing demand for sustainable and efficient synthetic methodologies. The introductory chapter of this thesis presents a comprehensive exploration of enamines and electro-redox chemistry, emphasizing their adaptability in a wide array of chemical reactions and their fundamental role in organic synthesis. Moving on to Chapter 2, the thesis unveils an electrochemical strategy designed for the synthesis of NH-pyrroles with unsymmetrical substitutions. This approach entails a complex heterocoupling process between two enamines with distinct structures, employing sequential chemoselective oxidation, addition, and cyclization steps. Importantly, the developed protocol exhibits equal efficacy in facilitating the homocoupling of enamines, resulting in the formation of symmetric pyrroles. Chapter 3 details an effective synthetic pathway for constructing N2-aryl 1,2,3-triazoles through sequential C−N bond formation, showcasing electro-oxidative N−N coupling under metal-free conditions. In Chapter 4, electrochemical organoselenium catalysis is explored for the selective activation of alkynes, providing convenient access to carbonyl-pyrroles/oxazoles from N-propargyl enamines/amides. Chapter 5 introduces a metal- and oxidant-free electrocatalytic approach to produce structurally significant azabicyclic scaffolds from N-allyl enamine carboxylates. Furthermore, Chapter 6 details the synthesis of quinoxalines through copper-electrocatalytic azidation/annulation cascade at low catalyst loading. Chapter 7 describes the iodide-catalyzed electro-oxidative skeletal rearrangement of 3-Aminoindazoles for the synthesis of 1,2,3- benzotriazine, incorporating an amine derivative. Finally, Chapter 8 delves into cutting-edge developments in electrochemical iodide-sulphoxide dual catalysis, specifically tailored for the synthesis of disubstituted 2-oxopyrrolidines.

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