Enantioselective conjugate addition reactions to α,β-unsaturated-α,γ-substituted-2,5-cyclohexadienones
| dc.contributor.advisor | Majewski, Marek | en_US |
| dc.contributor.advisor | Abrams, Sue | en_US |
| dc.contributor.committeeMember | Gravel, Michel | en_US |
| dc.creator | Mulligan, Kirk Michael | en_US |
| dc.date.accessioned | 2007-11-28T10:32:40Z | en_US |
| dc.date.accessioned | 2013-01-04T05:09:17Z | |
| dc.date.available | 2008-12-03T08:00:00Z | en_US |
| dc.date.available | 2013-01-04T05:09:17Z | |
| dc.date.created | 2007-12 | en_US |
| dc.date.issued | 2007-12-03 | en_US |
| dc.date.submitted | December 2007 | en_US |
| dc.description.abstract | Enantioselective conjugate addition (ECA) reactions between organometallic reagents and cyclohexadienone 165 are being investigated. Previous studies have shown that ECAs, of organometallic reagents to á,â-unsaturated cyclohexadienones, are useful in many natural product syntheses. The substrates used in earlier studies were simple 2,5-cyclohexadienones, with a proton at the C-3 position, resulting in the synthesis of a trisubstituted C-3 atom. ECAs that afford all-carbon quaternary stereogenic centers are a much more challenging problem and few examples have been reported. Some natural products contain a ã-hydroxy group, however, no ECA substrates have incorporated this motif. ECAs have been accomplished with substrates having a g-ether substituent. The cyclohexadienone 165 system presents three challenging problems to overcome for an ECA reaction: the tertiary methyl substituents at the 3 and 5 positions, facial selectivity and enantioselectivity. An ECA to 165 using an organoaluminum reagent and an external chiral ligand 26 was successful in producing a product that showed the reaction was moderately stereoselective. A diastereoselective conjugate addition reaction (DCA) to 165 using a chiral auxiliary 68 was also successful in producing a product that showed the reaction was moderately enantioenriched. Lastly, a variable temperature NMR study was performed to establish the presence of dynamic motions of the C=N bond present in sulfinyl imines 229 and 230. As a result, the sulfinyl imines 229 and 230 were found to be interconverting at -78°C. | en_US |
| dc.identifier.uri | http://hdl.handle.net/10388/etd-11282007-103240 | en_US |
| dc.language.iso | en_US | en_US |
| dc.subject | Cyclohexadienones | en_US |
| dc.subject | Stereoselectivity | en_US |
| dc.subject | Conjugate Addition | en_US |
| dc.title | Enantioselective conjugate addition reactions to α,β-unsaturated-α,γ-substituted-2,5-cyclohexadienones | en_US |
| dc.type.genre | Thesis | en_US |
| dc.type.material | text | en_US |
| thesis.degree.department | Chemistry | en_US |
| thesis.degree.discipline | Chemistry | en_US |
| thesis.degree.grantor | University of Saskatchewan | en_US |
| thesis.degree.level | Masters | en_US |
| thesis.degree.name | Master of Science (M.Sc.) | en_US |