Novel iodine mediated carbocyclisations and hypervalent iodine(III) reagents

• Main Author: Khan, Zulfiqar Ali
• Published: Cardiff University 2010
• Subjects: 547.6; QD Chemistry
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.584787

The first chapter focuses on the introduction of iodine mediated carbocyclisations and their applications continue to present a stimulating challenge in target- and diversity-oriented synthesis. The second chapter discusses applications and brief literature overview about classical approaches towards the syntheses of indene derivatives. Herein the syntheses of 3-iodo-1 H-indene derivatives via iodonium-promoted 5-endo-dig carbocyclisation of 2-substituted ethynylmalonates as a key starting material are described. Within this study, we were able to show that the 3-iodo-1 H-indene can be used as a synthetic platform not only for the palladium chemistry but also as a catalyst for the in situ generation of [text unavailable] hypervalent iodine reagent. Additionally, 3-iodo-1 H-indene derivatives have the potential to perform asymmetric synthesis. Third chapter demonstrates tandem iodine mediated carboannulation of the stilbene malonate derivatives via either 5-exo- or 6-endo-trig mode under basic reagents with subsequent lactonisation to structurally complex indanes and tetrahydronaphthalenes with three new stereogenic centres. In the present study, a unique stereochemistry was observed in the case of tetrahydroindenofuranones and confirmed by single crystal X-ray analysis. These cyclisations proceed exclusively with the retention of configuration to form tetrahydroindenofuranones. Both the compounds formed as a single diastereomers as judged from their 1H and 13C NMR spectrum. In fourth chapter the synthesis of novel simplified analogues of IBA by oxidation of [text unavailable] diiodoacrylic acids are described. Additionally, the ligand exchange resulted in tosylate derivative. The new reagents have been utilized in various well established oxidative transformations with superior or similar reactivity as conventional hypervalent iodine(III) reagents.