The addition of lithium dienolate 130, formed from ethyl 2-bromocrotonate, to enones and aldehydes yielding vinylcyclopropanes and vinyloxiranes was optimized. Various methods, pyrolytic and nonpyrolytic, were examined for the rearrangement of the resulting vinylcyclopropanes to cyclopentenes in an overall [2+3] annulation sequence. During the course of these studies, a new rearrangement pathway of these vinylcyclopropanes to bridged [3.2.n] bicyclic systems was discovered thus establishing a new [3+4] annulation technology.
The extension of the [2+3] annulation technology to oxygenated cyclopentanoids was addressed. Several ethyl 2-bromo-4-oxycrotonates were synthesized, and the reaction of their lithium dienolates (217) with enones was investigated. The rearrangement of the resulting enol ether terminated vinylcyclopropanes to oxygenated cyclopentenes was also examined.
[see document for diagram of chemical reaction]
The application of this methodology was expressed in a synthetic approach to (-)-specionin (109). The key steps in this synthesis involved the cyclopropanation of optically pure enone 147 with Iithium dienolate 155 to give vinylcyclopropanes 169-exo/endo and the rearrangement of 169 to the oxygenated cyclopentanoid 187-exo which possesses the correct stereochemistry for further elaboration to epoxy acetate 216, an intermediate in a reported synthesis of specionin.
[see document for diagrams of chemical reactions] / Ph. D.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/54358 |
| Date | January 1989 |
| Creators | Fleming, Alison A. |
| Contributors | Chemistry, Hudlicky, Tomas, Wolfe, James F., Mason, John G., Tanko, James M., White, Robert H. |
| Publisher | Virginia Polytechnic Institute and State University |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation, Text |
| Format | vi, 171 leaves, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 21063568 |
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