Strategies toward protecting group-free glycosylation through selective activation of the anomeric center
- A. Michael Downey and
- Michal Hocek
Beilstein J. Org. Chem. 2017, 13, 1239–1279, doi:10.3762/bjoc.13.123
Graphical Abstract
Scheme 1: Solution-state conformations of D-glucose.
Scheme 2: Enzymatic synthesis of oligosaccharides.
Scheme 3: Enzymatic synthesis of a phosphorylated glycoprotein containing a mannose-6-phosphate (M6P)-termina...
Scheme 4: A) Selected GTs-mediated syntheses of oligosaccharides and other biologically active glycosides. B)...
Scheme 5: Enzymatic synthesis of nucleosides.
Scheme 6: Fischer glycosylation strategies.
Scheme 7: The basis of remote activation (adapted from [37]).
Scheme 8: Classic remote activation employing a MOP donor to access α-anomeric alcohols, carboxylates, and ph...
Figure 1: Synthesis of monoprotected glycosides from a (3-bromo-2-pyridyloxy) β-D-glycopyranosyl donor under ...
Scheme 9: Plausible mechanism for the synthesis of α-galactosides. TBDPS = tert-butyldiphenylsilyl.
Scheme 10: Synthesis of the 6-O-monoprotected galactopyranoside donor for remote activation.
Scheme 11: UDP-galactopyranose mutase-catalyzed isomerization of UDP-Galp to UDP-Galf.
Scheme 12: Synthesis of the 1-thioimidoyl galactofuranosyl donor.
Scheme 13: Glycosylation of MeOH using a self-activating donor in the absence of an external activator. a) Syn...
Scheme 14: The classical Lewis acid-catalyzed glycosylation.
Figure 2: Unprotected glycosyl donors used for the Lewis acid-catalyzed protecting group-free glycosylation r...
Scheme 15: Four-step synthesis of the phenyl β-galactothiopyranosyl donor.
Scheme 16: Protecting-group-free C3′-regioselective glycosylation of sucrose with α–F Glc.
Scheme 17: Synthesis of the α-fluoroglucosyl donor.
Figure 3: Protecting-group-free glycosyl donors and acceptors used in the Au(III)-catalyzed glycosylation.
Scheme 18: Synthesis of the mannosyl donor used in the study [62].
Scheme 19: The Pd-catalyzed stereoretentive glycosylation of arenes using anomeric stannane donors.
Scheme 20: Preparation of the protecting-group-free α and β-stannanes from advanced intermediates for stereoch...
Figure 4: Selective anomeric activating agents providing donors for direct activation of the anomeric carbon.
Scheme 21: One-step access to sugar oxazolines or 1,6-anhydrosugars.
Scheme 22: Enzymatic synthesis of a chitoheptaose using a mutant chitinase.
Scheme 23: One-pot access to glycosyl azides [73], dithiocarbamates [74], and aryl thiols using DMC activation and sub...
Scheme 24: Plausible reaction mechanism.
Scheme 25: Protecting-group-free synthesis of anomeric thiols from unprotected 2-deoxy-2-N-acetyl sugars.
Scheme 26: Protein conjugation of TTL221-PentK with a hyaluronan hexasaccharide thiol.
Scheme 27: Proposed mechanism.
Scheme 28: Direct two-step one-pot access to glycoconjugates through the in situ formation of the glycosyl azi...
Scheme 29: DMC as a phosphate-activating moiety for the synthesis of diphosphates. aβ-1,4-galactose transferas...
Figure 5: Triazinylmorpholinium salts as selective anomeric activating agents.
Scheme 30: One-step synthesis of DBT glycosides from unprotected sugars in aqueous medium.
Scheme 31: Postulated mechanism for the stereoselective formation of α-glycosides.
Scheme 32: DMT-donor synthesis used for metal-catalyzed glycosylation of simple alcohols.
Figure 6: Protecting group-free synthesis of glycosyl sulfonohydrazides (GSH).
Figure 7: The use of GSHs to access 1-O-phosphoryl and alkyl glycosides. A) Glycosylation of aliphatic alcoho...
Scheme 33: A) Proposed mechanism of glycosylation. B) Proposed mechanism for stereoselective azidation of the ...
Scheme 34: Mounting GlcNAc onto a sepharose solid support through a GSH donor.
Scheme 35: Lawesson’s reagent for the formation of 1,2-trans glycosides.
Scheme 36: Protecting-group-free protein conjugation via an in situ-formed thiol glycoside [98].
Scheme 37: pH-Specific glycosylation to functionalize SAMs on gold.
Figure 8: Protecting-group-free availability of phenolic glycosides under Mitsunobu conditions. DEAD = diethy...
Scheme 38: Accessing hydroxyazobenzenes under Mitsunobu conditions for the study of photoswitchable labels. DE...
Scheme 39: Stereoselective protecting-group-free glycosylation of D-glucose to provide the β-glucosyl benzoic ...
Figure 9: Direct synthesis of pyranosyl nucleosides from unactivated and unprotected ribose using optimized M...
Figure 10: Direct synthesis of furanosyl nucleosides from 5-O-monoprotected ribose in a one-pot glycosylation–...
Figure 11: Synthesis of ribofuranosides using a monoprotected ribosyl donor via an anhydrose intermediate.
Figure 12: C5′-modified nucleosides available under our conditions.
Scheme 40: Plausible reaction mechanism for the formation of the anhydrose.
Figure 13: Direct glycosylation of several aliphatic alcohols using catalytic Ti(Ot-Bu)4 in the presence of D-...
Figure 14: Access to glycosides using catalytic PPh3 and CBr4.
Figure 15: Access to ribofuranosyl glycosides as the major product under catalytic conditions. aLiOCl4 (2.0 eq...
