Date of Award
1994
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Abstract
A variety of bicyclic ketones was prepared and under strongly basic conditions (t-BuOK/t-BuOH/185{dollar}\sp\circ{dollar}C) their behaviour with respect to {dollar}\beta{dollar}-enolization was examined. Several new compounds were produced upon such treatment; these were identified on the basis of their {dollar}\rm\sp{lcub}13{rcub}Cmr{dollar} and {dollar}\rm\sp1Hmr{dollar} spectra.;3,3-Dimethylbicyclo (3.2.2) nonan-2-one slowly rearranged to 3,3-dimethylbicyclo (3.3.1) nonan-2-one, and the latter was stable. Similarly, 3,3-dimethylbicyclo (3.2.2) non-6-en-2-one rearranged to 3,3-dimethylbicyclo (3.3.1) non-6-en-2-one, which was not stable. Experiments with 3,3-dimethylbicyclo (3.3.1) non-6-en-2-one revealed that it was converted into five compounds. The major product, 2,2-dimethyl-4,5,6,7-tetra-hydrindan-1-one, arose from a {dollar}\beta{dollar}-enolate rearrangement. However, this enone underwent slow reduction to cis- and trans-8,8-dimethylbicyclo (4.3.0) nonan-7-one, presumably by single electron transfer from t-BuOK. As a result, the use of a {dollar}\beta{dollar}-enolate rearrangement in natural product synthesis was not considered worthwhile. Also, 3,3,7,7-tetramethylbicyclo- (3.3.1) nonan-2,6-dione was found to be reduced to 6-hydroxy-3,3,7,7-tetramethylbicyclo (3.3.1) nonan-2-one.;3,3-Dimethylbenzobicyclo (3.2.1) - and (2.2.2) octen-2-one and 3,3-dimethylbenzobicyclo (3.2.2) nonen-2-one were prepared and then examined under the same conditions as above. It was found that each rearranged to a single ketone; namely, 3,3-dimethyl-6,7-benzobicyclo (3.3.0) octen-2-one, 7,7-dimethyl-2,3-benzobicyclo (3.2.1) octen-6-one and 3,3-dimethyl-5,6-benzobicyclo (3.3.1) nonen-2-one, respectively. These rearrangement processes, however, are in competition with Haller-Bauer cleavage. The acids resulting from cleavage represented the major products of base treatment. This process precluded synthetic applications of {dollar}\beta{dollar}-enolate rearrangement in these systems.;The highly hindered alkoxide base, potassium 3-ethyl-3-pentoxide was prepared in an effort to retard the cleavage pathway, and while rearrangement was still observed, a predominance of cleavage products was again noted. The effect of several amide bases on the homoenolization of a variety of hindered ketones was also undertaken, in the hope of eliminating reduction caused by t-BuOK. Based on the results of this study, only N-lithio-9-azabicyclo (3.3.1) nonane (LABN) appeared to be worthy of further study, although for the systems studied herein, {dollar}\beta{dollar}-enolization was not observed when LABN was used as base.
Recommended Citation
Muir, David James, "Beta-enolization In Bicyclic Ketones" (1994). Digitized Theses. 2443.
https://ir.lib.uwo.ca/digitizedtheses/2443