This thesis describes the studies towards the functionalisation of arenes using gold(III) chloride and the total synthesis of (±)-polysiphenol, a naturally occurring bromophenol, isolated from Polysiphonia urceolata, a red alga of the family of Rhodomelaceae found in Chinese coastal waters.
The first chapter details the optimisation of the auration reaction of benzene and trapping of the intermediate species, PhAuCl2, with the use of a coordinating ligand. The isolation and characterisation of the aurated species, PhAuCl2.lut, is also discussed. The intermediate aurated species is utilised to achieve oxidative homocoupling, yielding biphenyl. The reaction is further expanded to a number of electron rich and mildly electron deficient aromatics. Attempts to render the reaction catalytic and to achieve oxidative heterocoupling are also described.
The second chapter illustrates the total synthesis of (±)-polysiphenol, via a biomimetically inspired highly regioselective intramolecular oxidative coupling route. The two bromine atoms are installed prior to oxidative coupling, preventing further oxidation to a planar aromatized phenanthrene, however attempts to brominate the aromatic rings following oxidative coupling, have also been carried out. The first synthesis of 1,1’-ethane-1,2-diylbis(2,5,6-tribromobenzene-3,4-diol), another natural product belonging to the family of Rhodomelaceae, is also described.
The last section of each chapter details the experimental protocols and spectral characterisation of all the compounds synthesised in this study.