Photo-Induced Generation of C and S-Centered Radicals: Reactivity and Applications Toward Cyclopropane Derivatives

Chandu, Palasetty (2023) Photo-Induced Generation of C and S-Centered Radicals: Reactivity and Applications Toward Cyclopropane Derivatives. PhD thesis, Indian Institute of Science Education and Research Kolkata.

Text (PhD thesis of Palasetty Chandu (16RS018)) 16RS018.pdf - Submitted Version Restricted to Repository staff only Download (16MB)

Abstract

Photoredox catalysis has become the most emerging research topic in synthetic organic chemistry in the last few decades. In this process, a photocatalyst uses visible light energy to trigger a catalytic redox process of a chemical reaction. In search of an eco-friendly alternative to the monopolistic usage of expensive transition metal catalysts, photo redox catalysis was first introduced at the beginning of this century with a few well-known metal complexes and organic dyes. The unique radical pathway, energy efficiency, and exceptionally milder reaction conditions make it famous in a decade. Widespread follow-through research in this field develops many new organo-photocatalyst to eliminate the expenses and environmental hazards of using transition metal-based photocatalysts like Ir, Ru, etc. And also open up the catalytic process's variable reactivity and tunability with plenty of accessible options. In this thesis, I elaborately demonstrated the application of photoredox catalysis to perform trifluoromethylation, difluoroalkylation, decarboxylative alkylation, thio-esterification, and sulfonylation of cyclopropane derivatives. The Cyclopropanes are the primitive building blocks having a wide range of reactivities attributing diverse options of functionalization. In the initial part of the thesis, the reactivity of different vinyl cyclopropanes has been examined towards various photogenerated short-lived radical intermediates for synthetically challenging allylic functionalization under a photocatalytic environment. Rest of the part of my thesis is more concentrated on the reactivity of the cyclopropenes with photocatalyzed hydro-sulfonylation, and a switchable competitive radical alkylation/sulfonylation strategy has been documented, including proper theoretical calculation supporting the selectivity of the reaction.

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