Preactivation-based chemoselective glycosylations: A powerful strategy for oligosaccharide assembly
- Weizhun Yang,
- Bo Yang,
- Sherif Ramadan and
- Xuefei Huang
Beilstein J. Org. Chem. 2017, 13, 2094–2114, doi:10.3762/bjoc.13.207
Graphical Abstract
Scheme 1: a) Traditional glycosylation typically employs the premixed approach with both the donor and the ac...
Scheme 2: Glycosylation of an unreactive substrate. Reagents and conditions: (a) Tf2O, −78 °C, CH2Cl2 (DCM), ...
Scheme 3: Bromoglycoside-mediated glycosylation.
Scheme 4: Glycosyl bromide-mediated selenoglycosyl donor-based iterative glycosylation. Reagents and conditio...
Scheme 5: Preactivation-based glycosylation using 2-pyridyl glycosyl donors.
Scheme 6: Chemoselective dehydrative glycosylation. Reagents and conditions: (a) Ph2SO, Tf2O, 2-chloropyridin...
Figure 1: Representative structures of products formed by the preactivation-based dehydrative glycosylation o...
Scheme 7: Possible mechanism for the dehydrative glycosylation. (a) Formation of diphenyl sulfide bis(triflat...
Scheme 8: Chemoselective iterative dehydrative glycosylation. Reagents and conditions: (a) Ph2SO, Tf2O, 2,4,6...
Scheme 9: Chemoselective iterative dehydrative glycosylation. Reagents and conditions: (a) Ph2SO, Tf2O, −40 °...
Scheme 10: Chemical synthesis of a hyaluronic acid (HA) trimer 47. Reagents and conditions: (a) Ph2SO, TTBP, CH...
Figure 2: Retrosynthetic analysis of pentasaccharide 48.
Scheme 11: Effects of anomeric leaving groups on glycosylation outcomes. Reagents and conditions: (a) Ph2SO, Tf...
Scheme 12: Reactivity-based one-pot chemoselective glycosylation.
Scheme 13: Preactivation-based iterative glycosylation of thioglycosides.
Scheme 14: BSP/Tf2O promoted synthesis of 75.
Scheme 15: Proposed mechanism for preactivation-based glycosylation strategy.
Figure 3: The preactivations of glycosyl donors 83, 85 and 87 were investigated by low temperature NMR, which...
Scheme 16: The more electron-rich glycosyl donor 91 gave a higher glycosylation yield than the glycosyl donor ...
Scheme 17: Comparison of the BSP/Tf2O and p-TolSCl/AgOTf promoter systems in facilitating the preactivation-ba...
Scheme 18: One-pot synthesis of Globo-H hexasaccharide 105 using building blocks 101, 102, 103 and 104.
Scheme 19: Synthesis of (a) oligosaccharides 109–113 towards (b) 30-mer galactan 115. Reagents and conditions:...
Figure 4: Structure of mycobacterial arabinogalactan 116.
Figure 5: Representative complex glycans from glycolipid family synthesized by the preactivation-based thiogl...
Figure 6: Representative microbial and mammalian oligosaccharides synthesized by the preactivation-based thio...
Figure 7: Some representative mammalian oligosaccharides synthesized by the preactivation-based thioglycoside...
Figure 8: Preparation of a heparan sulfate oligosaccharides library.
Scheme 20: Synthesis of oligo-glucosamines through electrochemical promoted preactivation-based thioglycoside ...
Scheme 21: Synthesis of 2-deoxyglucosides through preactivation. Reagents and conditions: a) AgOTf, p-TolSCl, ...
Scheme 22: Synthesis of tetrasaccharide 153. Reagents and conditions: (a) AgOTf, p-TolSCl, CH2Cl2, −78 °C; the...
Scheme 23: Aglycon transfer from a thioglycosyl acceptor to an activated donor can occur during preactivation-...
