20701-61-5Relevant articles and documents
Synthesis of Glucuronoxylan Hexasaccharides by Preactivation-Based Glycosylations
B?hm, Maximilian,Madsen, Robert,Underlin, Emilie N.,d'Errico, Clotilde
supporting information, (2020/05/16)
The synthesis of two glucuronoxylans is described, which both consist of a pentaxylan backbone and a glucuronic acid linked to the 2 position in the fourth xylose residue from the reducing end. The two target molecules differ in the 4 position of the glucuronic acid where one is unsubstituted while the other contains a methyl ether. The pentaxylan backbone is assembled in four glycosylation reactions with phenyl thioglycoside donors. The couplings are performed by preactivation of the donor with in-situ-generated p-nitrobenzenesulfenyl triflate prior to addition of the acceptor. The glucuronic acids are then attached by Koenigs-Knorr glycosylations followed by deprotections. The syntheses employ a total of 8 steps from monosaccharide building blocks and afford the two glucuronoxylans in 12 and 15 % overall yield. The hexasaccharide products are valuable substrates for investigating the activity and specificity of glucuronoxylan-degrading enzymes.
One-Pot Relay Glycosylation
Cai, Lei,Fang, Jing,Li, Ting,Song, Zejin,Sun, Jiuchang,Wan, Qian,Xiao, Xiong,Zeng, Jing
supporting information, p. 5498 - 5503 (2020/04/09)
A novel one-pot relay glycosylation has been established. The protocol is characterized by the construction of two glycosidic bonds with only one equivalent of triflic anhydride. This method capitalizes on the in situ generated cyclic-thiosulfonium ion as the relay activator, which directly activates the newly formed thioglycoside in one pot. A wide range of substrates are well-accommodated to furnish both linear and branched oligosaccharides. The synthetic utility and advantage of this method have been demonstrated by rapid access to naturally occurring phenylethanoid glycoside kankanoside F and resin glycoside merremoside D.
Automated access to well-defined ionic oligosaccharides
Delbianco, Martina,Grafmüller, Andrea,Schiefelbein, Kevin,Seeberger, Peter H.,Tyrikos-Ergas, Theodore,Zhu, Yuntao
supporting information, p. 1349 - 1353 (2020/03/03)
Ionic polysaccharides are part of many biological events, but lack structural characterisation due to challenging purifications and complex synthesis. Four monosaccharides bearing modifications not found in nature are used for the automated synthesis of a collection of ionic oligosaccharides. Structural analysis reveals how the charge pattern affects glycan conformation.
Efficient one-pot per-: O -acetylation-thioglycosidation of native sugars, 4,6- O -arylidenation and one-pot 4,6- O -benzylidenation-acetylation of S -/ O -glycosides catalyzed by Mg(OTf)2
Mukherjee, Mana Mohan,Basu, Nabamita,Chaudhury, Aritra,Ghosh, Rina
, p. 109301 - 109314 (2016/11/30)
A sequential one-pot per-O-acetylation-S-/O-glycosidation of native mono and disaccharides under solvent free conditions using 0.5 mole% of Mg(OTf)2 as a non-hygroscopic, recyclable catalyst is reported. Regioselective 4,6-O-arylidenation of glycosides and thioglycosides with benzaldehyde or p-methoxybenzaldehyde dimethyl acetal is catalyzed by 10 mole% of Mg(OTf)2 to produce the corresponding 4,6-O-arylidenated product in high yields. Mg(OTf)2 can also mediate sequential one-pot benzylidenation-acetylation of mono and disaccharide based glycosides and thioglycosides in high yield.
A Sugar-Based Gelator for Marine Oil-Spill Recovery
Vibhute, Amol M.,Muvvala, Venkatanarayana,Sureshan, Kana M.
supporting information, p. 7782 - 7785 (2016/07/07)
Marine oil spills constitute an environmental disaster with severe adverse effects on the economy and ecosystem. Phase-selective organogelators (PSOGs), molecules that can congeal oil selectively from oil–water mixtures, have been proposed to be useful for oil-spill recovery. However, a major drawback lies in the mode of application of the PSOG to an oil spill spread over a large area. The proposed method of using carrier solvents is impractical for various reasons. Direct application of the PSOG as a solid, although it would be ideal, is unknown, presumably owing to poor dispersion of the solid through the oil. We have designed five cheap and easy-to-make glucose-derived PSOGs that disperse in the oil phase uniformly when applied as a fine powder. These gelators were shown to selectively congeal many oils, including crude oil, from oil–water mixtures to form stable gels, which is an essential property for efficient oil-spill recovery. We have demonstrated that these PSOGs can be applied aerially as a solid powder onto a mixture of crude oil and sea water and the congealed oil can then be scooped out. Our innovative mode of application and low cost of the PSOG offers a practical solution to oil-spill recovery.
Three Solvent-Free Catalytic Approaches to the Acetal Functionalization of Carbohydrates and Their Applicability to One-Pot Generation of Orthogonally Protected Building Blocks
Traboni, Serena,Bedini, Emiliano,Giordano, Maddalena,Iadonisi, Alfonso
, p. 3562 - 3572 (2016/01/25)
Three alternative protocols were developed to carry out the selective installation of acetal groups on carbohydrates and polyols under mildly acidic, solvent-free conditions. One protocol is based on a diol/aldehyde condensation at room temperature, with an acetolysis process serving for the activation of the carbonyl component. A second approach is based on an orthoester-mediated activation of the carbonyl component at high temperature. The third protocol is instead entailing a transacetalation mechanism. Combination of these methods allows a wide set of acetal-protected building blocks to be accessed in short times under very simple experimental conditions working under air. The scope of the latter two approaches was also extended to unusual one-pot synthetic sequences leading to concomitant Fischer glycosidation/acetal protection of reducing sugars.
Exploring glycosylation reactions under continuous-flow conditions
Cancogni, Damiano,Lay, Luigi
supporting information, p. 2873 - 2878 (2015/01/16)
The industrial development of carbohydrate-based drugs is greatly thwarted by the typical challenges inherent in oligosaccharide synthesis. The practical advantages of continuous-flow synthesis in microreactors (high reproducibility, easy scalability, and fast reaction optimization) may offer an effective support to make carbohydrates more attractive targets for drug-discovery processes. Here we report a systematic exploration of the glycosylation reaction carried out under microfluidic conditions. Trichloroacetimidates and thioglycosides have been investigated as glycosyl donors, using both primary and secondary acceptors. Each microfluidic glycosylation has been compared with the corresponding batch reaction, in order to highlight advantages and drawbacks of microreactors technology. As a significant example of multistep continuous-flow synthesis, we also describe the preparation of a trisaccharide by means of two consecutive glycosylations performed in interconnected microreactors.
High-yield total synthesis of (-)-strictinin through intramolecular coupling of gallates
Michihata, Naoki,Kaneko, Yuki,Kasai, Yusuke,Tanigawa, Kotaro,Hirokane, Tsukasa,Higasa, Sho,Yamada, Hidetoshi
, p. 4319 - 4328 (2013/06/27)
This paper describes a total synthesis of (-)-strictinin, an ellagitannin that is 1-O-galloyl-4,6-O-(S)-hexahydroxydiphenoyl (HHDP)-β-d-glucose. In the study, total efficiency of the synthesis was improved to produce a 78% overall yield in 13 steps from d-glucose. In the synthesis, formation of the 4,6-(S)-HHDP bridge including the 11-membered bislactone ring was a key step, in which intramolecular aryl-aryl coupling was adopted. The coupling was oxidatively induced by CuCl2-n-BuNH2 with perfect control of the axial chirality, and the reaction conditions of this coupling were optimized thoroughly to achieve the quantitative formation of the bridge.
'Naked' and hydrated conformers of the conserved core pentasaccharide of N-linked glycoproteins and its building blocks
Barry, Conor S.,Cocinero, Emilio J.,Carcabal, Pierre,Gamblin, David P.,Stanca-Kaposta, E. Cristina,Remmert, Sarah M.,Fernandez-Alonso, Maria C.,Rudic, Svemir,Simons, John P.,Davis, Benjamin G.
supporting information, p. 16895 - 16903 (2013/12/04)
N-glycosylation of eukaryotic proteins is widespread and vital to survival. The pentasaccharide unit -Man3GlcNAc2- lies at the protein-junction core of all oligosaccharides attached to asparagine side chains during this process. Although its absolute conservation implies an indispensable role, associated perhaps with its structure, its unbiased conformation and the potential modulating role of solvation are unknown; both have now been explored through a combination of synthesis, laser spectroscopy, and computation. The proximal -GlcNAc-GlcNAc- unit acts as a rigid rod, while the central, and unusual, -Man-β-1,4-GlcNAc- linkage is more flexible and is modulated by the distal Man-α-1,3- and Man-α-1,6- branching units. Solvation stiffens the 'rod' but leaves the distal residues flexible, through a β-Man pivot, ensuring anchored projection from the protein shell while allowing flexible interaction of the distal portion of N-glycosylation with bulk water and biomolecular assemblies.
Contribution of phosphates and adenine to the potency of adenophostins at the IP3 receptor: Synthesis of all possible bisphosphates of adenophostin A
Sureshan, Kana M.,Riley, Andrew M.,Thomas, Mark P.,Tovey, Stephen C.,Taylor, Colin W.,Potter, Barry V. L.
supporting information; experimental part, p. 1706 - 1720 (2012/05/04)
Although adenophostin A (AdA), the most potent agonist of d-myo-inositol 1,4,5-trisphosphate receptors (IP3R), is thought to mimic IP 3, the relative roles of the different phosphate groups and the adenosine motif have not been established. We synthesized all three possible bisphosphate analogues of AdA and glucose 3,4-bisphosphate (7, AdA lacking the 2′-AMP). 2′-Dephospho-AdA (6) was prepared via a novel regioselective dephosphorylation strategy. Assessment of the abilities of these bisphosphates to stimulate intracellular Ca2+ release using recombinant rat type 1 IP3R (IP3R1) revealed that 6, a mimic of Ins(4,5)P2, is only 4-fold less potent than IP3, while 7 is some 400-fold weaker and even 3′3-dephospho-AdA (5) is measurably active, despite missing one of the vicinal bisphosphate groups normally thought to be crucial for IP3-like activity. Compound 6 is the most potent bisphosphate yet discovered with activity at IP3R. Thus, adenosine has a direct role independent of the 2′-phosphate group in contributing toward the potency of adenophostins, the vicinal bisphosphate motif is not essential for activity at the IP3R, as always thought, and it is possible to design potent agonists with just two of the three phosphates. A model with a possible adenine-R504 interaction supports the activity of 5 and 6 and also allows a reappraisal of the unexpected activity previously reported for the AdA regioisomer 2′3-phospho-3′3- dephospho-AdA 40.
