29741-67-1Relevant academic research and scientific papers
Aqueous Glycosylation of Unprotected Sucrose Employing Glycosyl Fluorides in the Presence of Calcium Ion and Trimethylamine
Pelletier, Guillaume,Zwicker, Aaron,Allen, C. Liana,Schepartz, Alanna,Miller, Scott J.
supporting information, p. 3175 - 3182 (2016/03/19)
We report a synthetic glycosylation reaction between sucrosyl acceptors and glycosyl fluoride donors to yield the derived trisaccharides. This reaction proceeds at room temperature in an aqueous solvent mixture. Calcium salts and a tertiary amine base promote the reaction with high site-selectivity for either the 3′-position or 1′-position of the fructofuranoside unit. Because nonenzymatic aqueous oligosaccharide syntheses are underdeveloped, mechanistic studies were carried out in order to identify the origin of the selectivity, which we hypothesized was related to the structure of the hydroxyl group array in sucrose. The solution conformation of various monodeoxysucrose analogs revealed the co-operative nature of the hydroxyl groups in mediating both this aqueous glycosyl bond-forming reaction and the site-selectivity at the same time.
Corrected order in the simultaneous debenzylation-acetolysis of methyl 2,3,4,6-tetra-O-benzyl-α-d-glucopyranoside
Cao, Yang,Yamada, Hidetoshi
, p. 909 - 911 (2007/10/03)
The benzyl groups of methyl 2,3,4,6-tetra-O-benzyl-α-d-glucopyranoside were cleaved in the order of 6-O-Bn > 3-O-Bn > 4-O-Bn > 2-O-Bn under acid-mediated conditions in acetic anhydride. The order is a correction of that previously reported.
Effects of lipid chain lengths in α-galactosylceramides on cytokine release by natural killer T cells
Goff, Randal D.,Gao, Ying,Mattner, Jochen,Zhou, Dapeng,Yin, Ning,Cantu III, Carlos,Teyton, Luc,Bendelac, Albert,Savage, Paul B.
, p. 13602 - 13603 (2007/10/03)
Glycolipid presentation by CD1 proteins has emerged as an important aspect of antigen recognition, and presentation of α-glycosylceramides by CD1d to natural killer T cells has become a central focus in understanding how glycolipid presentation can influence immune responses. An α-galactosylceramide containing relatively long lipid chains has been the subject of intense study because, when presented by CD1d to natural killer T cells, it stimulates the release of both proinflammatory and immunomodulatory cytokines. Using an efficient synthesis of α-galactosylceramides, we have prepared a series of glycolipids in which the lipid chain lengths have been incrementally varied. The responses of natural killer T cells to these glycolipids have been determined, and we have found that truncation of the phytosphingosine lipid chain increases the relative amounts of immunomodulatory cytokines released. In similar fashion, the length of the acyl chain in α-galactosylceramides influences cytokine release profiles. Copyright
Regio- and stereoselective synthesis of β-D-gluco-, α-L-ido-, and α- L-altropyranosiduronic acids from Δa4-uronates
Bazin, Helene G.,Wolff, Michael W.,Linhardt, Robert J.
, p. 144 - 152 (2007/10/03)
The stereoselective synthesis of β-D-glucopyranosiduronic, α-L- idopyranosiduronic, and α-L-altropyranosiduronic acids has been performed from different Δ4-uronate monosaccharides. Bromination of the C-4,5 double bond provided the trans-diaxial bromohydrin derivatives, which were converted to the corresponding epoxides in high yields. Direct reduction of the epoxides using boranetetrahydrofuran complex led to the corresponding glucuronic acids in low to good yields. Glucuronic acids were also obtained in satisfactory yields through a two-steps procedure involving bromination of the epoxide with titanium(IV) bromide followed by reduction using tributyltin hydride. Lewis acid-catalyzed rearrangement of these epoxides led to the corresponding α-L C-4 ketopyranosides adopting the 1C4 chair conformation. Hydride reduction afforded the α-L-idopyranosiduronic or the α-L- altropyranosiduronic acids, the stereoselectivity of the reduction being controlled by the appropriate substitution pattern.
