Wan, Shuangyi
(2008)
Total Synthesis of (+)-Dactylolide. Studies on the Cascade Cyclization Reactions of Epoxides/Polyepoxides Initiated by Single Electron Transfer.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
The total synthesis of the marine macrolactone (+)-dactylolide was achieved in a highly convergent and efficient way (Scheme I). The route involves the coupling of two functionalized fragments of the molecule, an ¦Á,¦Â-unsaturated aldehyde and a 1,3-syn-diol, to form a cyclic ¦Á,¦Â-unsaturated cyclic acetal. Both enantiopure fragments arise from asymmetric vinylogous Mukaiyama aldol reactions. The key transformations in this synthesis include a sequential Peterson olefination/Prins cyclization reaction to construct the 2,6-cis-disubstituted-4-methylenetetrahydropyran core efficiently and stereoselectively, a Mislow-Evans selenoxide-selenate [2,3] sigmatropic rearrangement to transpose allylic alcohol transposition and an intramolecular Horner-Emmons macrocyclization.A systematic study on the cascade cyclizations of epoxides/polyepoxides initiated by single electron transfer has been carried out (Scheme II). Four monoepoxides and six diepoxides were tested. The results showed that the bicyclo[3.1.0] epoxonium ion intermediates formed in the cyclization favor 5-exo-cyclization in the nonpolar solvent (1,2-dichloroethane) while in the polar solvent (CH3CN), they prefer 6-endo-selectivity. However, the bicyclo[4.1.0] epoxonium ion intermediates usually give 7-endo regiochemical selectivity in the presence of substitution-induced bias. However, without the substituent effect, 6-exo and 7-endo-cyclizations are two competitive pathways.
Share
| Citation/Export: |
|
| Social Networking: |
|
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Unpublished |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 | | | | | Committee Member | Brummond, Kay M | | | | | Committee Member | Koide, Kazunori | | | |
|
| Date: |
17 January 2008 |
| Date Type: |
Completion |
| Defense Date: |
17 January 2006 |
| Approval Date: |
17 January 2008 |
| Submission Date: |
4 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: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
cascade cyclization; epoxide; total synthesis |
| Other ID: |
http://etd.library.pitt.edu/ETD/available/etd-10042007-173306/, etd-10042007-173306 |
| Date Deposited: |
10 Nov 2011 20:02 |
| Last Modified: |
15 Nov 2016 13:50 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/9433 |
Metrics
Monthly Views for the past 3 years
Plum Analytics
Actions (login required)
 |
View Item |
![[feed]](/images/feed-icon-32x32.png){kind=icon}