| Summary: | This thesis is concerned primarily with the application of chiral organoborane reagents for asymmetric synthesis. A short chapter on the use of thexylborane N, N'-diethylaniline for reduction reactions is also included. The first chapter contains three main sections. The first (1.2) introduces the concepts of chirality and asymmetric synthesis, with discussions on mechanism, efficiency and importance of asymmetric synthesis. The second section (1.3), discusses the hydroboration reaction and reactions of organoboranes. The last section (1.4) reviews general developments in asymmetric synthesis followed by a detailed review of organoboron reagents in asymmetric synthesis. Chapters 2, 3 and 4 report attempts made to synthesise chiral monoalkylborane reagents from α-pinene (chapter 2), <i>trans</i>-verbenol derivatives (chapter 3) and nopol derivatives (chapter 4). The application of these chiral organoboranes for asymmetric hydroboration and, in some cases, reduction is discussed together with the enantiomeric yields achieved. The use of monoisopinocampheylborane and some chiral organoboranes derived from nopol for chiral hydroboration of trisubstituted alkenes, led to enantiomeric yields in excess of 70% . Chapter 5 reports the reducing properties of thexylborane N, N'-diethylaniline and compares the results with those from thexylborane reductions. The nature of the species present in this reagent was studied by infra-red spectrometry; the reagent was found to exist only partly in complexed form.
|
|---|
