Synthesis and reactivity of chiral hypervalent iodine compounds

Abstract

Hypervalent iodine compounds are molecules of increasing interest to the synthetic chemist. Their low toxicity when compared to heavy metal reagents and their ease of use in the laboratory are helping to establish them into the armoury of the synthetic chemist. More recently, research into chiral hypervalent iodine compounds has been the main focus. The work performed during this research tenure is based upon the development of new chiral hypervalent iodine reagents for use in stereoselective synthesis and this research can be summarised into three main sections: Synthesis of novel chiral iodine(III) compounds; Reactivity of chiral iodine(III) compounds; Novel oxididative procedure. The synthesis of new chiral iodine(III) compounds and their use in asymmetric oxidative functionalisations are described herein. The use of stoichiometric quantities of these iodine(III) reagents with 1 eq of pTsOHO in the a-oxytosylation of ketones and 2 eq of /7TSOH H2 O in the dioxytosylation of alkenes, have given the corresponding products in good yields, 57-76% (3-12% ee) and 48-75% (9-16% ee) respectively. Additionally, a new catalytic method is described in which the presence of a stoichiometric oxidant, 1 eq of /7TSOH H2O and only catalytic quantities of the chiral iodine(I) reagent is necessary to afford a-oxytosylated ketones. The final aspect of the research has dealt with the problems associated with oxidizing iodine(I) compounds to iodine(III) compounds. The development of a new method to oxidise iodine(I) compounds to bis(trifluoroacetoxy)iodo arenes through the use of urea-hydrogen peroxide adduct and trifluoroacetic anhydride is also described.EThOS - Electronic Theses Online ServiceGBUnited Kingdo