Iridium-promoted deoxyglycoside synthesis : stereoselectivity and mechanistic insight
Herein, we devised a method for stereoselective O-glycosylation using an Ir(I)-catalyst which enables both hydroalkoxylation and nucleophilic substitution of glycals with varying substituents at the C3 position. In this transformation, 2-deoxy-α-O-glycosides were acquired when glycals equipped with...
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| Main Authors: | , , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
| Published: |
2021
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| Subjects: | |
| Online Access: | https://hdl.handle.net/10356/147077 |
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| Institution: | Nanyang Technological University |
| Language: | English |
| Summary: | Herein, we devised a method for stereoselective O-glycosylation using an Ir(I)-catalyst which enables both hydroalkoxylation and nucleophilic substitution of glycals with varying substituents at the C3 position. In this transformation, 2-deoxy-α-O-glycosides were acquired when glycals equipped with a notoriously poor leaving group at C3 were used; in contrast 2,3-unsaturated-α-O-glycosides were produced from glycals that bear a good leaving group at C3. Mechanistic studies indicate that both reactions proceed via the directing mechanism, through which the acceptor coordinates to the Ir(I) metal in the α-face-coordinated Ir(I)-glycal π-complex and then attacks the glycal that contains the O-glycosidic bond in a syn-addition manner. This protocol exhibits good functional group tolerance and is exemplified with the preparation of a library of oligosaccharides in moderate to high yields and with excellent stereoselectivities. |
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