Studies on the synthesis of tetrahydropyrans via oxa-Michael addition leading towards the total synthesis of Montanacin D
The first chapter describes a facile stereochemical study and synthetic route towards di-substituted tetrahydropyran rings. The key steps performed in this section involve cross-metathesis and Ozone-Wittig reactions of each alkene substrate, followed by an efficient oxa-Michael cyclisation to give t...
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| Format: | Thesis-Doctor of Philosophy |
| Language: | English |
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Nanyang Technological University
2021
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| Online Access: | https://hdl.handle.net/10356/148132 |
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| Institution: | Nanyang Technological University |
| Language: | English |
| Summary: | The first chapter describes a facile stereochemical study and synthetic route towards di-substituted tetrahydropyran rings. The key steps performed in this section involve cross-metathesis and Ozone-Wittig reactions of each alkene substrate, followed by an efficient oxa-Michael cyclisation to give the di-substituted tetrahydropyran products in good yields. These tetrahydropyrans adopt chair-like conformations where diequatorial products are exclusively obtained under kinetic control.
The second and third chapters explore an efficient total synthetic route towards Montanacin D. Considered as a unique member of its family, Montanacin D is of great interest as the tetrahydropyran is adjacent to the butenolide moiety, which provides conformational rigidity. The approach to the molecule is done by way of a convergent synthesis, where the key reactions involve high diastereoselectivity in the oxa-Michael step in mild conditions and a more efficient manner of forming the alkene bonds – methods established in the previous chapter. |
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