Exploring and exploiting the reactivity of glycals in organic synthesis
Chapter 1 introduces that glycals as one type of unsaturated carbohydrates specialized with a double bond between C1 and C2 on the sugar ring. They demonstrated diverse reactivities and broad applications in organic synthesis, owing to their availability, affordable price and chemical structure with...
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| Other Authors: | |
| Format: | Thesis |
| Language: | English |
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2018
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| Online Access: | https://hdl.handle.net/10356/82506 http://hdl.handle.net/10220/46643 |
| _version_ | 1826129725469229056 |
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| author | Yao, Hui |
| author2 | Liu Xuewei |
| author_facet | Liu Xuewei Yao, Hui |
| author_sort | Yao, Hui |
| collection | NTU |
| description | Chapter 1 introduces that glycals as one type of unsaturated carbohydrates specialized with a double bond between C1 and C2 on the sugar ring. They demonstrated diverse reactivities and broad applications in organic synthesis, owing to their availability, affordable price and chemical structure with defined chiral centers. Glycals could not only be explored as a glycosyl donor in glycosylation which is the core of carbohydrate chemistry, but also be exploited efficiently as natural chiral pools in total syntheses of natural/unnatural products.
In chapter 2, we have developed the first successful catalyst-controlled O-glycosylation via palladium catalysis using 3,4-cyclic carbonate glycal as the glycosyl donor. Various 2,3-unsaturated glycosides with C4-OH were synthesized stereoselectively in high yields under mild reaction condition. While hard nucleophiles such as aliphatic alcohols gave β-glycosides, soft nucleophiles such as phenols produced α-glycosides because palladium(II) catalyst coordinated with glycals on the β-face by carbonate group direction. On the other hand, both aliphatic alcohols and phenols generated only β-glycosides directed by hydrogen-bond effect because palladium(0) catalyst coordinated with glycal from α-face due to the steric hindrance. This method serves as a concise approach for constructing glycosides with predictable stereoselectivity and could potentially be applied to the formation of oligosaccharides and natural products. |
| first_indexed | 2024-10-01T07:45:12Z |
| format | Thesis |
| id | ntu-10356/82506 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T07:45:12Z |
| publishDate | 2018 |
| record_format | dspace |
| spelling | ntu-10356/825062023-02-28T23:55:15Z Exploring and exploiting the reactivity of glycals in organic synthesis Yao, Hui Liu Xuewei School of Physical and Mathematical Sciences DRNTU::Science::Chemistry Chapter 1 introduces that glycals as one type of unsaturated carbohydrates specialized with a double bond between C1 and C2 on the sugar ring. They demonstrated diverse reactivities and broad applications in organic synthesis, owing to their availability, affordable price and chemical structure with defined chiral centers. Glycals could not only be explored as a glycosyl donor in glycosylation which is the core of carbohydrate chemistry, but also be exploited efficiently as natural chiral pools in total syntheses of natural/unnatural products. In chapter 2, we have developed the first successful catalyst-controlled O-glycosylation via palladium catalysis using 3,4-cyclic carbonate glycal as the glycosyl donor. Various 2,3-unsaturated glycosides with C4-OH were synthesized stereoselectively in high yields under mild reaction condition. While hard nucleophiles such as aliphatic alcohols gave β-glycosides, soft nucleophiles such as phenols produced α-glycosides because palladium(II) catalyst coordinated with glycals on the β-face by carbonate group direction. On the other hand, both aliphatic alcohols and phenols generated only β-glycosides directed by hydrogen-bond effect because palladium(0) catalyst coordinated with glycal from α-face due to the steric hindrance. This method serves as a concise approach for constructing glycosides with predictable stereoselectivity and could potentially be applied to the formation of oligosaccharides and natural products. Doctor of Philosophy 2018-11-14T04:54:32Z 2019-12-06T14:56:58Z 2018-11-14T04:54:32Z 2019-12-06T14:56:58Z 2018 Thesis Yao, H. (2018). Exploring and exploiting the reactivity of glycals in organic synthesis. Doctoral thesis, Nanyang Technological University, Singapore. https://hdl.handle.net/10356/82506 http://hdl.handle.net/10220/46643 10.32657/10220/46643 en 203 p. application/pdf |
| spellingShingle | DRNTU::Science::Chemistry Yao, Hui Exploring and exploiting the reactivity of glycals in organic synthesis |
| title | Exploring and exploiting the reactivity of glycals in organic synthesis |
| title_full | Exploring and exploiting the reactivity of glycals in organic synthesis |
| title_fullStr | Exploring and exploiting the reactivity of glycals in organic synthesis |
| title_full_unstemmed | Exploring and exploiting the reactivity of glycals in organic synthesis |
| title_short | Exploring and exploiting the reactivity of glycals in organic synthesis |
| title_sort | exploring and exploiting the reactivity of glycals in organic synthesis |
| topic | DRNTU::Science::Chemistry |
| url | https://hdl.handle.net/10356/82506 http://hdl.handle.net/10220/46643 |
| work_keys_str_mv | AT yaohui exploringandexploitingthereactivityofglycalsinorganicsynthesis |