Copper(I) Catalyzed Synthesis of Phenols and Benzo[d]isothiazol- 3-ones and their Application for the Synthesis of Alkyl Aryl Ethers and Benzo[d]isothiazol-3-one-1-oxides
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The thesis is divided into five chapters. The first chapter is a general introduction and describes the scope of copper-catalyzed C-N, C-O and C-S bond formation with examples. It also describes the various mechanistic pathways proposed for the reactions.The next two chapters describe copper catalyzed hydroxylation of aryl halides and the one pot conversion the resultant phenoxides to aryl alkyl ethers. The forth and fifth chapters are devoted to the copper catalyzed synthesis of N-substituted benzo[d]isothizol-3-ones and subsequent titanium catalyzed oxidation to N-substituted benzo[d]isothiazol-3-one-1-oxide. Chapter 1. Copper-Catalyzed C-N, C-O and C-S Cross-Coupling Reactions The copper catalyzed carbon-heteroatom bond formation has evolved as a major synthetic pathway in the last decade. In comparison to palladium based catalysts, they are cheap, less toxic and easily available. In this chapter, a brief review of methods already available in the literature for C-N, C-O and C-S cross-coupling reactions has been provided. Also, a brief review of the various mechanistic pathways proposed for these reactions is discussed. Chapter 2. Copper(I)-Catalyzed Selective Hydroxylation of Aryl Halides Phenols and their derivatives are structural constituents of numerous natural products, pharmaceuticals and polymers. Transition metal catalyzed C-O cross-coupling reactions have been looked upon as a feasible alternative for the synthesis of phenols from aryl halides. In this chapter we have described a selective hydroxylation of aryl iodides and aryl bromides with tetrabutylammonium hydroxide, as a nucleophile catalyzed by a combination of CuI and 8- hydroxyquinalidine in a 2:3 mixture of DMSO-water. The procedure is efficient, general and simple to afford substituted phenols (Scheme 1).
Supervisor: Tharmalingam Punniyamurthy