Organoiodine Promoted Strategies for the Construction of Selected Bioactive Heterocycles

Abstract

Organoiodine reagents have been extensively used in plethora of organic transformations to assemble medicinally important azaheterocycles because of their safety profile, mild reaction conditions and high newlineyields of pure products. The recent surge of organoiodine-based reactions as potential alternatives to transition metal-catalyzed reactions led to the development of many novel synthetic protocols by devoiding the usage of ligands, additives and excess reagents. In view of economic and environmental consideration, new and improved catalytic methods involving organoiodine reagents should become an area of major focus to facilitates the synthesis of bioactive heterocycles in more sustainable fashion. This thesis deals with the utility of organoiodine reagents in the development of new synthetic routes to construct medicinally important azaheterocycles via C-C and C-X bond formations. The first chapter highlights the recent advancement of organoiodine reagents in the construction of biologically important azaheterocycles and natural products. Especially synthesis, reactivity and applications of diaryliodonium salts in the carbon-carbon and carbon-heteroatom bond formations for the constructions of valuable heterocyclic frameworks under metal and metal-free conditions are briefly explained in this chapter. Additionally, significance of natural and synthetic bisindole analogues and azaheterocylces in cancer drug discovery are also elaborated. The second chapter illustrates the synthesis of novel 2,5-bis(indolyl)-1,3,4-oxadiazoles by iodobenzene newlinediacetate-mediated oxidative cyclization of easily accessible bis(indolyl)hydrazide-hydrazones involving relatively benign reaction conditions. All of the synthesized oxadiazoles showed improved cytotoxicity newlineover previously reported bis(indolyl)heterocycles. Bromo-substituted bis(indolyl)1,3,4-oxadiazole was the most active compound in the series with IC50 value of 20 nm against prostate (DU145) and cervical (HeLa) cancer cell lines. The structure activity relationship study