Construction of C-C bonds by photocatalysis via radical addition cascade cyclization (RACC) : Synthesis of heteroatom-containing small molecules

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PhD; 2022; Organic chemistry

The thesis presents photocatalytic methods for synthesizing small organic molecules at room temperature. The thesis is divided into four sections. Section A presents the general introduction to the thesis. Section B is presented as a single chapter, which describes an intramolecular ipso-arylative cyclization of aryl alkynoate with tricarbonyl compounds under photocatalytic conditions via radical addition cascade cyclization (RACC). The methodology could be extended to the arylpropiolamides and arylthioates as well. Section C is presented in two Chapters, Chapters 3 and 4. Chapter 3 describes a visible light-mediated difunctionalization of activated alkynes to form coumarin and spirolactones. The coumarins and spirolactones could be formed selectively by tuning the substituent present in the aryl alkynoate. The spirolactones synthesized in this method can be transformed into complex spirocyclic structures under a separate visible light-mediated reaction. Chapter 4 describes a visible light-mediated radical addition cascade cyclization (RACC) between maleimides and phenethylboronic acids to access fused tetrahydro-1H-benzo[e]isoindole-1,3(2H)-diones. The last section is presented as Chapter 5, which deals with a photocatalytic approach to the direct acylation of electron-deficient heteroarenes. The methodology could be used to synthesize biologically active small molecules.