Wang, Lijun
(2005)
CARBON-CARBON BOND CONSTRUCTION USING ELECTRON TRANSFER INITIATED CYCLIZATION REACTIONS. RUTHENIUM-CATALYZED HYDROESTERIFICATION AND ITS APPLICATION TOWARDS THE SYNTHESIS OF INTEGRAMYCIN.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Electron transfer initiated cyclization reactions were successfully applied to the construction of carbon-carbon bonds after tuning the chemoselectivity and reactivity of the substrates. Olefins and allenes with several different electron-donating groups served as good nucleophiles in cyclization reactions to generate various carbocycles. Cascade cyclizations involving C-C bond formation also proved to be successful. In most cases, cyclizations gave good to excellent yields with short reaction times. A general protocol has been developed for synthesizing lactones from allylic and homoallylic alcohols using ruthenium-catalyzed hydroesterifications. The lactone synthesis only requires 1-2 steps and can be conducted in one pot. The experimental procedure is simple and the efficiency is considerably improved compared to that of multi-step sequences. Mechanistic studies with deuterium labeling showed that the competition between hydrometalation, β-hydride elimination, and reductive elimination determines the efficiency and regioselectivity of the hydroesterification reactions. Two major fragments of integramycin have been synthesized. The synthesis of the C16-C35 spiroketal unit of integramycin was accomplished in a convergent and stereoselective manner. The sequence includes the usage of a highly efficient ruthenium-mediated hydroesterification reaction. This sequence also demonstrates the efficiency of C,O-dianioic additions into lactones as a method for producing spiroketals in a single operation without recourse to extensive protecting group manipulations. The synthesis of the cis-decalin unit of integramycin was achieved using a cycloaddition and an allylic rearrangement as key steps. The dienyne substrate of the cycloaddition was synthesized enantioselectively in 36% yield over 9 steps. The conditions of the cycloaddition using [(naph)Rh(cod)]SbF6 were optimized and the diastereoselectivity of the cycloaddition was found to be temperature and solvent dependant.
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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Unpublished |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 | Floreancig, Paul E | florean@pitt.edu | FLOREAN | | | Committee Member | Day, Billy | | | | | Committee Member | Curran, Dennis P | | | | | Committee Member | Brummond, Kay | | | |
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| Date: |
10 October 2005 |
| Date Type: |
Completion |
| Defense Date: |
19 July 2005 |
| Approval Date: |
10 October 2005 |
| Submission Date: |
21 July 2005 |
| 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: |
carbocycle; cis-decalin; cycloaddition; integramycin; lactone; spiroketal |
| Other ID: |
http://etd.library.pitt.edu/ETD/available/etd-07212005-205619/, etd-07212005-205619 |
| Date Deposited: |
10 Nov 2011 19:52 |
| Last Modified: |
15 Nov 2016 13:46 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/8483 |
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