A new, general method for the asymmetric synthesis of quaternary carbons is described. This technique involves stereocontrolled generation of alpha,alpha-disubstituted amide enolates via reduction of bicyclic alpha,alpha-disubstituted alpha-thioglycolate lactams using one-electron transfer reagents. A model of the geometric constraints necessary to reductively prepare alpha,alpha-disubstituted amide enolates with control of enolate E/Z stereochemistry is described and several chiral auxiliaries were prepared to test this design. / Successful preparation, trapping, isolation and characterization of alpha,alpha-disubstituted amide enolates is described. This reductive enolization method allows, for the first time, the stereoselective preparation of both E- and Z-acyclic alpha,alpha-disubstituted amide enolates. / Reactivity and selectivity of alpha,alpha-disubstituted amide enolates in alkylation with alkyl halides is explored. Dichotomous reactivity is observed for both E- and Z-alpha,alpha-disubstituted amide enolates. Z-alpha,alpha-Disubstituted amide enolates are shown to alkylate with high levels of stereoselectivity; E-alpha,alpha-disubstituted amide enolates alkylate with poor stereoselectivity. / Methods for isolation of the quaternary carbon-containing adducts are described. Conditions for the determination of the enantiomeric excess of chiral, non-racemic neopentyl alcohols were developed and are also described. / Development of a facile, environmentally friendly, modular synthesis of a model second-generation chiral auxiliary using simple, inexpensive starting materials is described.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.82927 |
| Date | January 2003 |
| Creators | Manthorpe, Jeffrey Michael |
| Contributors | Gleason, James L. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Chemistry.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001983789, proquestno: AAINQ88523, Theses scanned by UMI/ProQuest. |
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