166021-01-8Relevant articles and documents
Diastereoselective cyclopropanation of electron-deficient alkenes via metal glycal carbenes
Otto, Frank,Doetz, Karl Heinz
, p. 2183 - 2190 (2008)
Silyl- and isopropylidene-O-protected chromium glucal and galactal carbenes have been synthesized from their glycal precursors according to the Fischer route. NMR studies indicate a preferred 5H4 or 4H5 conformation, depending on the nature of the protective group and the configuration at C-4. The complexes with glycal carbenes have been applied to the diastereoselective cyclopropanation of methyl crotonate and γ-crotonolactone. Georg Thieme Verlag Stuttgart.
Me3SI-promoted chemoselective deacetylation: a general and mild protocol
Gurawa, Aakanksha,Kashyap, Sudhir,Kumar, Manoj
, p. 19310 - 19315 (2021/06/03)
A Me3SI-mediated simple and efficient protocol for the chemoselective deprotection of acetyl groups has been developedviaemploying KMnO4as an additive. This chemoselective deacetylation is amenable to a wide range of substrates, tolerating diverse and sensitive functional groups in carbohydrates, amino acids, natural products, heterocycles, and general scaffolds. The protocol is attractive because it uses an environmentally benign reagent system to perform quantitative and clean transformations under ambient conditions.
General Strategy for Stereoselective Synthesis of β- N-Glycosyl Sulfonamides via Palladium-Catalyzed Glycosylation
Dai, Yuanwei,Zheng, Jianfeng,Zhang, Qiang
supporting information, p. 3923 - 3927 (2018/07/21)
A highly efficient and mild glycosylation reaction between 3,4-O-carbonate glycal and N-tosyl functionalized aliphatic and aromatic amines via palladium-catalyzed decarboxylative allylation is disclosed. A wide range of highly functionalized 2,3-unsaturat
Stereoselective glycosylation of 2-nitrogalactals catalyzed by a bifunctional organocatalyst
Medina, Sandra,Harper, Matthew J.,Balmond, Edward I.,Miranda, Silvia,Crisenza, Giacomo E. M.,Coe, Diane M.,McGarrigle, Eoghan M.,Galan, M. Carmen
supporting information, p. 4222 - 4225 (2016/09/09)
The use of a bifunctional cinchona/thiourea organocatalyst for the direct and α-stereoselective glycosylation of 2-nitrogalactals is demonstrated for the first time. The conditions are mild, practical, and applicable to a wide range of glycoside acceptors with products being isolated in good to excellent yields. The method is exemplified in the synthesis of mucin type Core 6 and 7 glycopeptides.
Cross-coupling reaction of saccharide-based alkenyl boronic acids with aryl halides: The synthesis of bergenin
Parkan, Kamil,Pohl, Radek,Kotora, Martin
supporting information, p. 4414 - 4419 (2014/05/06)
A convenient synthetic pathway enabling D-glucal and D-galactal pinacol boronates to be prepared in good isolated yields was achieved. Both pinacol boronates were tested in a series of cross-coupling reactions under Suzuki-Miyaura cross-coupling conditions to obtain the corresponding aryl, heteroaryl, and alkenyl derivatives in high isolated yields. This methodology was applied to the formal synthesis of the glucopyranoside moiety of papulacandin D and the first total synthesis of bergenin. Building blocks with boron: A convenient synthetic route to D-glucal and D-galactal pinacol boronates was developed, and the boronates were used in cross-coupling reactions to generate the corresponding aryl, heteroaryl, and alkenyl derivatives in high yields (see scheme). This methodology was applied to the formal synthesis of the glucopyranoside moiety of papulacandin D and the total synthesis of bergenin.
α-Selective organocatalytic synthesis of 2-deoxygalactosides
Balmond, Edward I.,Coe, Diane M.,Galan, M. Carmen,McGarrigle, Eoghan M.
supporting information, p. 9152 - 9155 (2012/10/29)
Alpha rules: A thiourea acts as an efficient organocatalyst for the glycosylation of protected galactals to form oligosaccharides containing a 2-deoxymonosaccharide moiety (see scheme). The reaction is highly stereoselective for α-linkages and proceeds by way of a syn-addition mechanism. Copyright
Immunomodulating glycosphingolipids: An efficient synthesis of a 2′-deoxy-α-galactosyl-GSL
Costantino, Valeria,Fattorusso, Ernesto,Imperatore, Concetta,Mangoni, Alfonso
, p. 369 - 375 (2007/10/03)
A new and efficient approach to the total synthesis of 2′-deoxy-α-galactosyl glycosphingolipids was accomplished. Commercially available 3,4,6-tri-O-acetylgalactal was used as the chiral starting material for both the sugar and phytosphingosine building blocks required for the synthesis of 1-O-(2-deoxy-α-D-galactopyranosyl)-2-docosanoylamino-1,3, 4-octadecanetriol. The key step of the synthetic strategy was the stereoselective α-glycosidation of the azido precursor of sphingosine.
Synthesis of Asialo GM1. New insights in the application of sulfonamidoglycosylation in oligosaccharide assembly: Subtle proximity effects in the stereochemical governance of glycosidation
Kwon, Ohyun,Danishefsky, Samuel J.
, p. 1588 - 1599 (2007/10/03)
The total synthesis of asialo GM1 (1a) has been accomplished. Using related chemistry, the methyl glycoside of the asialo compound (1b) has also been synthesized. These kinds of compounds have been identified as potential ligands for bacterial and viral infection sites. A simpler structure, which has also been identified for its infection attracting structure in the context of glycopeptides and glycolipids (methyl glycoside 2), has also been synthesized. The key common phase in the syntheses involves the sulfonamidoglycosidation reaction which is used to create a β-linkage leading to a ga1NAc residue joined to the C4 hydroxyl group of a galactose unit either as a monosaccharide (see compound 2) or as C4' in the context of a lactosyl moiety. During the course of these studies there was encountered an unusual 'proximal hydroxyl' directing effect. Thus, when C4 on the galactose ring of an azaglycosylating donor bears a free hydroxyl (see, for instance, compound 13), β-glycoside formation predominates. When this hydroxyl group is blocked, the process tends in the direction of α-glycoside formation (see compound 32). These findings were explained as arising from a critical intramolecular hydrogen bond between the C4 axial hydroxyl of the galactose donor and its proximal pyranosidal ring oxygen. This interaction stabilizes conformations from which β-glycosidation predominates.
