Xu, Xuan
(2006)
Catalytic, Asymmetric Synthesis of â-Lactams with Cinchona Alkaloid Catalysts.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
In 2004, our group found with TMS protected quinine and quinidine as catalysts, -lactones can be synthesized with high diastereoselectivity and enantioselectivity by acyl-halide aldehyde cyclocondensation (AAC) reactions (Scheme I). Based on the success of AAC methodology in our group, we want to check the potential for the application of the same protocol in the asymmetric â-lactam synthesis (Scheme II). Instead of aldehyde, imines will be chosen as substrates for the [2+2] cycloaddition. We want to know that with some activation group at nitrogen atom, whether we can get some active substrates. In addition, if the imine substrates are not very active, would Lewis acid provide sufficient activations to imines? If the substituted ketenes are substrates, what would the diastereoselectivity be? The activation group at N atom was chosen as nitrobenzenesulfonyl group and the R1 substituent can be aromatic groups (Scheme III). The yields and ee values were good. In this project, we extend the successful protocol in AAC chemistry to the asymmetric â-lactam synthesis. In our system, benzenesulfonyl group is proved to be a good choice of activation group. Because of the small energy difference in the transition state for the reaction between alkyl group substituted ketene and activated imine substrate, low diastereoselectivity was obtained.
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| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
29 June 2006 |
| Date Type: |
Completion |
| Defense Date: |
23 January 2006 |
| Approval Date: |
29 June 2006 |
| Submission Date: |
24 April 2006 |
| 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: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
â-Lactam; Alkaloid Catalyst; asymmetric synthesis |
| Other ID: |
http://etd.library.pitt.edu/ETD/available/etd-04242006-101539/, etd-04242006-101539 |
| Date Deposited: |
10 Nov 2011 19:41 |
| Last Modified: |
15 Nov 2016 13:42 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/7585 |
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