Topic
Glycal
About: Glycal is a research topic. Over the lifetime, 897 publications have been published within this topic receiving 17422 citations.
Papers published on a yearly basis
Papers
More filters
••
TL;DR: In this paper, a mild method for the synthesis of 2-deoxysugars from the coupling of glycals with a range of nucleophiles is described, which employs 1 mol % of an air and moisture-tolerant rhenium−oxo complex [ReOCl3(SMe2)(Ph3PO)] as a catalyst for the formation of O-, N-, and S-α-glycosides.
Abstract: A mild method for the synthesis of 2-deoxysugars from the coupling of glycals with a range of nucleophiles is described. The method employs 1 mol % of an air- and moisture-tolerant rhenium−oxo complex [ReOCl3(SMe2)(Ph3PO)] as a catalyst for the formation of O-, N-, and S-α-glycosides. The catalytic system tolerates a number of commonly employed protecting groups, including isopropylidene acetals, alkyl and silyl ethers, acetates, and benzoates. Furthermore, the high-oxidation-state complex selectively catalyzes the coupling with the glycal acceptor in preference to oxidation of the glycals, alcohols, and even thiols.
138 citations
••
TL;DR: The combination of the glycosylation and subsequent functionalization provides a novel entry to saccharides which are otherwise difficult to prepare and should make this method a useful tool in synthetic carbohydrate chemistry.
Abstract: A highly stereoselective palladium-catalyzed O-glycosylation reaction is described. The reaction of a glycal 3-acetate or carbonate with the zinc(II) alkoxide of acceptors establishes the glycosidic linkage under palladium catalysis to give rise to disaccharides as the product in good yields and with high stereoselectivity. In contrast to the Lewis acid mediated Ferrier procedure, the anomeric stereochemistry of this reaction is controlled by the employed ligand. Whereas the use of a complex of palladium acetate and 2-di(tert-butyl)phosphinobiphenyl as the catalyst results in the exclusive beta-glycoside formation, the same reaction using trimethyl phosphite ligand furnishes an alpha-anomer as the major product. The utility of the 2,3-unsaturation present in the resulting glycoside is demonstrated by the further transformations such as dihydroxylation, hydration, and hydrogenation reactions. Thus, the combination of the glycosylation and subsequent functionalization provides a novel entry to saccharides which are otherwise difficult to prepare. The broad scope of the process, mildness of the reaction conditions, and experimental simplicity should make this method a useful tool in synthetic carbohydrate chemistry.
137 citations
•
TL;DR: The presence of the mannose isomer has been revealed by extension of the 19F-NMR analyses to other literature methods for 2-FDG synthesis involving the electrophilic fluorinating agent acetyl hypofluorite.
Abstract: The reaction of [F-18]F2 with D-glucal in water proceeds sufficiently mildly at room temperature to present marked regiospecificity. After hydrolysis, analysis by Fourier-transform 19F-NMR showed the product to consist of a mixture of 2-fluoro-2-deoxy-D-glucose (2-FDG) and 2-fluoro-2-deoxy-D-mannose (2-FDM) in a 2:1 ratio, respectively. The presence of the mannose isomer has been revealed by extension of the 19F-NMR analyses to other literature methods for 2-FDG synthesis involving the electrophilic fluorinating agent acetyl hypofluorite. Reaction of acetyl [F-18] hypofluorite, prepared by the reaction of [F-18]F2 with solid sodium acetate trihydrate, with the appropriate glycal/solvent combination, followed by hydrolysis, has led to production of [F-18]2-FDG with a radiochemical purity of 95%.
120 citations
••
TL;DR: Differentially protected Glycosyl phosphates prepared by a straightforward synthesis from glycal precursors are used as powerful glycosyl donors and an orthogonal coupling strategy using glycosol phosphate donors and thioethyl glycoside acceptors allows for the rapid synthesis of a trisaccharide.
120 citations
••
TL;DR: The first was constructed by intermolecular coupling of an indole anion with a 1,2-anhydrosugar derived from an endo-glycal by direct epoxidation as discussed by the authors.
Abstract: The total syntheses of staurosporine and ent-staurosporine have been achieved. Both glycosidic bonds were built from glycal precursors. The first was constructed by intermolecular coupling of an indole anion with a 1,2-anhydrosugar derived from an endo-glycal by direct epoxidation. The second bond was assembled from an exo-glycal by intramolecular iodoglycosylation.
114 citations