Rearrangements of acyclic epoxides
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
The BF₃-catalysed rearrangements of three epoxy-cholestanes have been reinvestigated. The products isolated from these reactions were markedly dependent of the solvent. A novel fragmentation (and recyclisation) mechanism is postulated to account for the occurrence of 4α-hydroxy compounds from the 4β,5β-epoxide (4). The preference for hydrogen, relative to deuterium, migration in the rearrangement of monodeuterated isobutene oxide (48) to give isobutyraldehyde has been measured. The BF₃-catalysed rearrangement of the unsymmetrical epoxide (63) to give aldehyde (112) was found to proceed by selective migration (ca. 1.9:1) of the hydrogen atom (Hb) trans to the t-butyl group. The syntheses and rearrangements of sterospecifically monodeuterated derivatives (64) and (65) are described. Mechanistic implications of the above results are discussed.