Shen, Xiaoqiang
(2008)
Catalytic Asymmetric Synthesis of β-Lactones and Application to the Total Synthesis of (-)-Pironetin.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
The Al-triamine complex catalyzed acyl halide-aldehyde cyclocondensation (AAC) reactions, developed previously by the Nelson group, have been extended to asymmetric AAC reactions of alkyl-substituted ketenes with structurally diverse aldehydes. By using of 2nd generation Al-triamine complex as catalyst, benzotrifluoride as solvent, the disubstituted β-lactones were synthesized in high yields and excellent enantioselectivities from readily available starting materials.Another conceptionally different methodology has also been developed to synthesize enantioenriched β-lactones. The concept of double activation has been applied in this reaction technology to accelerate the β-lactones formation. By using of cinchona alkaloids to activate ketenes, and at the same time utilizing of lithium salts to activate aldehydes, Wynberg's [2+2] cycloaddition protocol has been greatly expanded to a variety of aldehydes. Stereoenriched β-lactones derived from either Al-triamine or cinchona alkaloids catalyzed asymmetric acyl halide-aldehyde cyclocondensation (AAC) have been untilized in natural product synthesis. An asymmetric total synthesis of the antitumor agent pironetin was pursued using β-lactone templates for establishing all the requisite stereochemical relationships.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
| Title | Member | Email Address | Pitt Username | ORCID |
|---|
| Committee Chair | Nelson, Scott G | | | | | Committee Member | Doemling, Alexander S | | | | | Committee Member | Curran, Dennis P | | | | | Committee Member | Floreancig, Paul E | | | |
|
| Date: |
29 January 2008 |
| Date Type: |
Completion |
| Defense Date: |
23 August 2007 |
| Approval Date: |
29 January 2008 |
| Submission Date: |
8 October 2007 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Chemistry |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
β-Lactones; Asymmetric Catalysis; Pironetin; Total Synthesis |
| Other ID: |
http://etd.library.pitt.edu/ETD/available/etd-10082007-193252/, etd-10082007-193252 |
| Date Deposited: |
10 Nov 2011 20:02 |
| Last Modified: |
15 Nov 2016 13:50 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/9447 |
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