- Stereoselective O-Glycosylations by Pyrylium Salt Organocatalysis**
-
Despite many years of invention, the field of carbohydrate chemistry remains rather inaccessible to non-specialists, which limits the scientific impact and reach of the discoveries made in the field. Aiming to increase the availability of stereoselective
- Nielsen, Michael Martin,Holmstr?m, Thomas,Pedersen, Christian Marcus
-
supporting information
(2021/12/30)
-
- Electrochemical Synthesis of Glycosyl Fluorides Using Sulfur(VI) Hexafluoride as the Fluorinating Agent
-
This manuscript describes the electrochemical synthesis of 17 different glycosyl fluorides in 73-98% yields on up to a 5 g scale that relies on the use of SF6 as an inexpensive and safe fluorinating agent. Cyclic voltammetry and related mechanistic studies carried out subsequently suggest that the active fluorinating species generated through the cathodic reduction of SF6 are transient under these reductive conditions and that the sulfur and fluoride byproducts are effectively scavenged by Zn(II) to generate benign salts.
- Kim, Sungjin,Nagorny, Pavel
-
p. 2294 - 2298
(2022/04/07)
-
- Deuterium labelling to extract local stereochemical information by VCD spectroscopy in the C-D stretching region: A case study of sugars
-
Stereochemical elucidation of molecules with multiple chiral centers is difficult. Even with VCD spectroscopy, excluding all but one diastereomeric structural candidate is challenging because the stereochemical inversion of one chiral center among many centers does not always result in noticeable differences in their VCD spectra. This work demonstrates that the introduction of a suitable VCD chromophore with absorption in the 2300-1900 cm-1 region can be used for extracting local stereochemical information and for the stereochemical assignment of the C-1 position of various sugars as a case study. Through studies on a series of epimeric pairs of monosaccharides and their derivatives, we found that the introduction of one -OCD3 group to each C-1 position produced almost mirror-image VCD patterns in the 2300-1900 cm-1 region depending on the C-1 stereochemistry irrespective of the other molecular moieties. This work also shows that comparison of the observed VCD signals and the calculated ones enables the stereochemical assignment of a chiral center in the vicinity of the chromophore. This study provides a proof of concept that the use of a VCD chromophore in the 2300-1900 cm-1 region enables the analysis of selected stereochemistry of suitable molecular systems. Further studies on this concept should lead to the development of a method useful for the structural elucidation of other types of complex molecules.
- Abdelrasoul, Mariam,Abe, Yoshihiro,Maulida, Nurul Fajry,Monde, Kenji,Nakamura, Yuta,Taniguchi, Tohru,Zubir, Mohamad Zarif Mohd
-
p. 1067 - 1072
(2022/02/11)
-
- Synthesis of Glycosyl Fluorides by Photochemical Fluorination with Sulfur(VI) Hexafluoride
-
This study describes a new convenient method for the photocatalytic generation of glycosyl fluorides using sulfur(VI) hexafluoride as an inexpensive and safe fluorinating agent and 4,4′-dimethoxybenzophenone as a readily available organic photocatalyst. This mild method was employed to generate 16 different glycosyl fluorides, including the substrates with acid and base labile functionalities, in yields of 43%-97%, and it was applied in continuous flow to accomplish fluorination on an 7.7 g scale and 93% yield.
- Bannykh, Anton,Khomutnyk, Yaroslav,Kim, Sungjin,Nagorny, Pavel
-
supporting information
p. 190 - 194
(2021/01/13)
-
- Total Synthesis of Phospholipomannan of Candida albicans
-
First, total synthesis of the cell surface phospholipomannan anchor [β-Manp-(1 → 2)-β-Manp]n-(1 → 2)-β-Manp-(1 → 2)-α-Manp-1 → P-(O → 6)-α-Manp-(1 → 2)-Inositol-1-P-(O → 1)-phytoceramide of Candida albicans is reported. The target phospholipomannan (PLM) anchor poses synthetic challenges such as the unusual kinetically controlled (1 → 2)-β-oligomannan domain, anomeric phosphodiester, and unique phytoceramide lipid tail linked to the glycan through a phosphate group. The synthesis of PLM anchor was accomplished using a convergent block synthetic approach using three main appropriately protected building blocks: (1 → 2)-β-tetramannan repeats, pseudodisaccharide, and phytoceramide-1-H-phosphonate. The most challenging (1 → 2)-β-tetramannan domain was synthesized in one pot using the preactivation method. The phytoceramide-1-H-phosphonate was synthesized through an enantioselective A3 three-component coupling reaction. Finally, the phytoceramide-1-H-phosphonate moiety was coupled with pseudodisaccharide followed by deacetylation to produce the acceptor, which on subsequent coupling with tetramannosyl-H-phosphonate provided the fully protected PLM anchor. Final deprotection was successfully achieved by Pearlman's hydrogenation.
- Ali, Asif,Gannedi, Veeranjaneyulu,Singh, Parvinder Pal,Vishwakarma, Ram A.
-
p. 7757 - 7771
(2020/07/25)
-
- Synthesis and conformational analysis of phosphorylated β-(1→2) linked mannosides
-
Phosphorylated β-(1→2)-oligomannosides are found on the cell surface of several Candida species, including Candida albicans (an opportunistic pathogen). These molecules are believed to take part in the invasion process of fungal infections, which in the case of C. albicans can lead to severe bloodstream infections and death, and can therefore be considered important from a biological standpoint. Understanding the mechanism of their action requires access to the corresponding oligosaccharide model compounds in pure form. In the present work, synthesis of the model core structures involved in the invasion process of C. albicans, consisting of phosphorylated β-(1→2)-linked mannotriose and tetraose, is reported. In order to elucidate the nature of these molecules in more detail, an extensive NMR-spectroscopic study encompassing complete spectral characterization, conformational analysis and molecular modelling was performed. The obtained results were also compared to similar chemical entities devoid of the charged phosphate group.
- Rahkila, Jani,Ekholm, Filip S.,Panchadhayee, Rajib,Arda, Ana,Canada, Francisco Javier,Jimenez-Barbero, Jesus,Leino, Reko
-
supporting information
p. 58 - 68
(2014/01/06)
-
- FeCl3 mediated arylidenation of carbohydrates
-
Glycosides and thioglycosides based on monosaccharides in reaction with benzaldehyde dimethylacetal or p-methoxybenzaldehyde dimethyl acetal undergo FeCl3-catalyzed (20 mol %) regioselective 4,6-O-arylidenation producing the corresponding acetals in high yields. FeCl3 also mediates acetalation of glycosides and thioglycosides of cellobiose, maltose, and lactose affording the corresponding 4′,6′-O-benzylidene acetals, which were isolated after their acetylation in situ with acetic anhydride and pyridine. The combined yields (two steps) of these final products are also high (61-84%). The procedure is applicable to a wide variety of functional groups including -OBn.
- Basu, Nabamita,Maity, Sajal K.,Roy, Soumik,Singha, Shuvendu,Ghosh, Rina
-
experimental part
p. 534 - 539
(2011/04/27)
-
- Synthesis of |β-(1→2)-linked oligomannosides
-
β-(1→2)-Linked oligomannosides constitute an important class of carbohydrate structures located on the cell surface of several Candida species, including C. albicans. As a result of the immunostimulating properties of such compounds, the upscaling of their synthesis is relevant. In this paper, a highly stereoselective synthesis of |β-(1→2)-linked oligomannosides was performed by further development of and modifications to the methodologies described earlier in the literature. In addition to the synthesis of fully deprotected β-(1→2)-linked mannobiose and mannotriose, some preliminary modifications to the oligosaccharide core, resulting in close analogues with biological potential, are presented. The fully deprotected products form potential targets for screening against C. albicans and may also result in new model structures for vaccine development.
- Polakova, Monika,Roslund, Mattias U.,Ekholm, Filip S.,Saloranta, Tiina,Leino, Reko
-
scheme or table
p. 870 - 888
(2009/07/17)
-
- Synthesis of the repeating trisaccharide unit of the cell wall lipopolysaccharide of Escherichia coli type 8
-
NIS/TfOH mediated glycosidation of methyl 3,4,6-tri-O-benzyl-α-d-mannopyranoside with phenyl 2-O-acetyl-3,4,6-tri-O-benzyl-1-thio-α-d-mannopyranoside furnished the corresponding disaccharide derivative in excellent yield and α-selectivity. Ze?mplen deacet
- Maity, Sajal K.,Maity, Swarupananda,Patra, Amarendra,Ghosh, Rina
-
scheme or table
p. 5847 - 5849
(2009/04/05)
-
- Automated solid-phase synthesis of protected oligosaccharides containing β-mannosidic linkages
-
For automated oligosaccharide synthesis to impact glycobiology, synthetic access to most carbohydrates has to become efficient and routine. Methods to install "difficult" glycosidic linkages have to be established and incorporated into the overall synthet
- Codee, Jeroen D. C.,Kroeck, Lenz,Castagner, Bastien,Seeberger, Peter H.
-
supporting information; experimental part
p. 3987 - 3994
(2009/05/27)
-
- Synthesis of 2-O-(3-O-carbamoyl-α-D-mannopyranosyl)-L-gulopyranose: Sugar moiety of antitumor antibiotic bleomycin
-
A new route to the disaccharide moiety (2-O-(3-O-carbamoyl-α-D-mannopyranosyl)-L-gulopyranose) of the antitumor agent bleomycin was developed. Both the L-gulose synthon 21 and the 3-O-carbamoyl-D-mannose segment 30 were prepared from D-mannose in a regioselective manner by applying stannylene acetal methodology. Glycosylation of 21 with 30 proceeded smoothly, and further conversion to disaccharide derivatives (33 and 34) was successfully accomplished.
- Oshitari, Tetsuta,Shibasaki, Masakatsu,Yoshizawa, Takeshi,Tomita, Masahiro,Takao, Ken-Ichi,Kobayashi, Susumu
-
p. 10993 - 11006
(2007/10/03)
-
- New method for the preparation of L-gulose from D-mannose: Synthetic study on the sugar moiety of bleomycin
-
L-gulose, a key building block of the carbohydrate moiety of antitumor antibiotic bleomycins, is prepared from D-mannose by the inversion at C-5.
- Oshitari, Tetsuta,Tomita, Masahiro,Kobayashi, Susumu
-
p. 6493 - 6494
(2007/10/02)
-