Investigation of iodonium salts : synthesis, stability and reactivity

This thesis describes several approaches to the synthesis of novel iodonium salts. Firstly, attempts to synthesise a variety of novel alkynyl(aryl)iodonium salts (i-iii) is discussed. Most of these attempts were unsuccessful, however, useful information for future work was obtaine. The synthesis of iodonium salt (iii) was successful and this compound displayed some unusual reactivity. Several alkynyl(phenyl)iodonium trifluoroacetates were synthesised directly from commercially available iodobenzene diacetate and terminal acetylenes precursors with a range of substitution patterns in one step in excellent yields. These species were converted into alkenyl(arylsulfonyl)iodonium tetrafluoroborates in excellent yields by stereoselective Michael-type addition of arylsulfinic acids under protic conditions. Secondly, new reactivity of alkenyl(arylsulfonyl)iodonium tetrafluoroborates was investigated. Specially, the conversion of these selectively into aldehydes and vinyl chlorides using aqueous DMSO was achieved. Thirdly, two examples of stable enynyl(phenyl)iodonium trifluoroacetates were synthesised in excellent yields. These were converted into a new range of dienyl(aryl)iodonium salts. Finally, a computational study of alkynyl(aryl)iodonium salts was undertaken in an attempt to rationalise our experimental data on reactivity and stability.