Novel methods for the synthesis of small ring systems

Abstract

Chapter 1 briefly reviews telescoped reactions, in particular tandem oxidation processes, detailing the background to the development of the methodology presented here, and sets out the aims for the Thesis. Chapter 2 reviews cyclopropanation methods and examines the preparation and use of triisopropylsulfoxonium tetrafluoroborate II for the preparation of gemdimethylcyclopropanes for a range of α,β-unsaturated compounds including ketones, esters, amides, nitriles and nitro-compounds (Scheme I). Chapter 2 also examines potential applications for the methodology, outlining a route towards the synthesis of chrysanthemic acid as well as attempts towards rearrangement methodology. Chapter 3 demonstrates the preparation of 3-substituted oxindoles from substituted anilides in a copper-mediated cyclisation-decarboxylation sequence (Scheme II). This sequence is demonstrated for a range of alkyl, aryl and heteroaryl substituents in the 3-position, with methyl, benzyl and PMB protection on the nitrogen atom. Further development of the copper-cyclisation methodology leading to a catalytic system is presented, along with initial work towards a decarboxylative allylation of oxindoles.