Novel Iodine Mediated Carbocyclisations and Hypervalent Iodine(iii) Reagents

The first chapter focuses on the introduction of iodine m ediated carbocyclisations and their applications continue to present a stim ulating challenge in targetand diversityoriented syntheses. Literature overview of m ore than past two decades about this area of research has been highlighted by including key examples along with the ir m echanistic aspects. The second chapter discusses applications and literature synopsis about classical approaches tow ards the syntheses of indene derivatives. Herein the syntheses of 3-iodol//-in d en e derivatives by way of iodonium -prom oted 5-endo-dig carbocyclisation of 2 substitu ted ethynylm alonates as a key starting m aterial are described. The Sonogashira cross-coupling reaction is utilised as a key step in order to access 2 substitu ted ethynylm alonates as a starting material. A range of term inal acetylenes bearing aromatic, aliphatic and propargylic moieties can be employed to boost the scope of reaction. Further 3-iodo-l//-indene derivatives elaborated on using the Mizoroki-Heck reaction to form new C-C bond for further structural diversity. W ithin this study, we w ere able to show for the first time that the 3-iodo-l//-indene can be used as a synthetic platform not only for the palladium chem istry bu t also as a catalyst for the in situ generation of A3-hypervalent iodine reagen t Additionally, 3 -iodo-l//-indene derivatives have the potential to perform asymmetric syntheses. :OOEt COOEt EtOOC. COOEt I2 , basic reagents I The third chapter dem onstrates tandem iodine m ediated carboannulation of the stilbene m alonate derivatives via either S-exoor 6 -endo-trig mode under basic reagents w ith subsequent lactonisation to structurally complex indanes and te trahydronaphthalenes with th ree new stereogenic centres. The overall transform ation entails the associated formation of one strategic carbon-carbon and one carbon-oxygen bonds leading to a tricyclic indane and tetrahydronaphthalene compounds from acyclic precursors in one synthetic operation. In the p resen t study, a unique stereochem istry w as observed in the case of tetrahydroindenofuranones and confirmed by single crystal X-ray analysis. While the stereochem istry of tetrahydronaphthalene derivatives is established by the spectroscopic techniques. Both the com pounds form ed as a single d iastereom ers as judged from their *H and 13C NMR spectra. A literatu re overview of synthetic m ethodologies and applications of the indane and tetrahydronaphthalene derivatives is also incorporated in the th ird chapter. H3COOC. .COOCH3 I2, basic reagents COOMe COOMe O 5-exo-trig 6-endo-trig In the fourth chapter the syntheses of novel simplified analogues of IBA by oxidation of a,p-diiodoacrylic acids are described. The oxidation of (2T)-2,3-diiodobut-2-enoic acid w ith various oxidants resulted in the successful form ation of AM odane analogue. Additionally, AModane derivative is transform ed to its respective tosylate derivative by the reaction of pTsOH. These new reagents have been utilized in a variety of well established oxidative transform ations as mild oxidants w ith elevated or com parable reactivity as conventional hypervalent iodine(III) reagents.