8-O-Sialylation of Neuraminic Acid
| Autor: | Richard R. Schmidt, Yury E. Tsvetkov, Julio C. Castro-Palomino |
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| Rok vydání: | 1998 |
| Předmět: | |
| Zdroj: | Journal of the American Chemical Society. 120:5434-5440 |
| ISSN: | 1520-5126 0002-7863 |
| DOI: | 10.1021/ja9740327 |
| Popis: | Synthesis of Neu5Acα(2−3)Galβ(1−4)Glc and Neu5Acα(2−8)Neu5Ac derivatives 12α and 14α, from lactose derivative 6 and 2,3-dehydro-Neu5Ac derivative 7, respectively, with anchimerically assisted Neu5Ac donor 3e, 3f, or 3g has been studied. Reaction of halogenose 3e, having a 3-phenoxythiocarbonyloxy moiety as the assisting group, afforded with 6 and 7 in the presence of equimolar amounts of AgOTf as promoter α-sialosides 11α and 13α which were readily deoxygenated to afford 12α and 14α, respectively. Reaction of phosphite 3f, having a 3-bromo substituent as the potentially anchimeric assisting group, furnished in the presence of catalytic amounts of TMSOTf with 6 as acceptor α-sialoside 15α and with 7 as acceptor β-sialoside 17β, which gave on debromination 12α and 14β, respectively. Reaction of readily available phosphite 3g, having a 3-thiobenzoyloxy group as the anchimeric assisting group, afforded with 6 and 7 in the presence of catalytic amounts of TMSOTf in very high yields α-linked sialosides 21α and ... |
| Databáze: | OpenAIRE |
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