120403-27-2Relevant academic research and scientific papers
Rapid Synthesis of l-Idosyl Glycosyl Donors from α-Thioglucosides for the Preparation of Heparin Disaccharides
Herczeg, Mihály,Demeter, Fruzsina,Balogh, Tímea,Kelemen, Viktor,Borbás, Anikó
supporting information, p. 3312 - 3316 (2018/07/13)
A new methodology for the synthesis of the most challenging heparin building block has been developed. Orthogonally protected l-idosyl glycosyl donors were prepared by C5 epimerization of the corresponding thioglucosides using the hydroboration/oxidation method followed by a 4,6-acetal formation. The α-anomeric configuration was crucial, and the bulky C4 substituent was advantageous for the high l-ido diastereoselectivity. The 4,6-arylmethylene group proved to be a directing element in glycosylation, whereby stereoselective α-idosylation could be achieved by using idosyl donors without a C-2 participating group.
Novel approaches for the synthesis and activation of thio- and selenoglycoside donors
Valerio, Silvia,Iadonisi, Alfonso,Adinolfi, Matteo,Ravida, Alessandra
, p. 6097 - 6106 (2008/02/09)
(Chemical Equation Presented) Alkyl thio-, phenyl seleno-, and phenyl thioglycosides can be prepared through short synthetic sequences based on the generation of glycosyl iodides as versatile intermediates. In addition, a novel cheap combined system (stoichiometric NBS and catalytic Bi(OTf)3) has been developed for rapid and efficient activation of a wide variety of thio- and selenoglycoside donors.
Synthesis of cis-(1 → 3)-glycosides of allyl 2-acetamido-4,6-O- benzylidene-2-deoxy-α-D-glucopyranoside
Madaj, Janusz,Jankowska, Magdalena,Wisniewski, Andrzej
, p. 1293 - 1300 (2007/10/03)
Syntheses of allyl 2,3,4-tri-O-benzyl-α-D-gluco- and D-galactopyranosyluronate-(1→3)-2-acetamido-4,6-O-benzylidene-2-deoxy- α-D-glucopyranoside via oxidation of the hydroxymethyl group of allyl 2,3,4-tri-O-benzyl-α-D-gluco- and D-galactopyranosyl-(1→3)-2-
Synthesis and absolute configuration of lepidimoide, a high potent allelopathic substance from mucilage of germinated cress seeds
Kosemura,Yamamura,Kakuta,Mizutani,Hasegawa
, p. 2653 - 2656 (2007/10/02)
Lepidimoide (1), 1,2-cis-linked dissacharide, was synthesized from D-glucose and α-L-rhamnose for determination of the absolute configuration.
Use of the methylsulfenyl cation as an activator for glycosylation reactions with alkyl (aryl) 1-thioglycopyranosides: synthesis of methyl O-(2-acetamido-2- deoxy-beta-D-glucopyranosyl)-(1----6)-O-alpha-D-glucopyranosyl-(1----2) -alpha-D -glucopyranoside, a derivative of the core trisaccharide of E. coli K12.
Dasgupta,Garegg
, p. 225 - 238 (2007/10/02)
Methylsulfenyl bromide (MSB) and methylsulfenyl trifluoromethanesulfonate (MST) have been used to prepare 1,2-cis-linked disaccharides. Ethyl (phenyl) 1-thio-beta-D-gluco- and galacto-pyranosides having non-participating (benzyloxy) protecting groups were used as the donors. The alpha beta-ratio of the products depended on the promoter and conditions of reaction. Intimate ion-pairs, formed initially, may be responsible for the steric outcome of the glycosylations. Thus, with ethyl 2,3,4,6-tetra-O-benzyl-alpha-D-mannopyranoside as a donor, moderate quantities of the beta-linked disaccharide could be produced using MSB as the activator. The synthesis of the title trisaccharide glycoside that contains 1,2-cis and 1,2-trans-linkages is described.
SYSTEMATIC CHEMICAL SYNTHESIS AND N.M.R. SPECTRA OF METHYL α-GLYCOSIDES OF ISOMALTO-OLIGOSACCHARIDES AND RELATED COMPOUNDS
Kovac, Pavol,Lerner, Laura
, p. 87 - 112 (2007/10/02)
Acid-catalyzed thiophenolysis of 1,6-anhydro-2,3,4-tri-O-benzyl-β-D-glucopyranose and acetylation of the resulting phenyl 2,3,4-tri-O-benzyl-1-thio-α-D-glucopyranoside (4) gave phenyl 6-O-acetyl-2,3,4-tri-O-benzyl-1-thio-α-D-glucopyranoside (5).Reaction of 5 with chlorine gave, stereospecifically, the corresponding β-glycosyl chloride, which was treated with 4 in the presence of silver perchlorate and 2,4,6-trimethylpyridine to afford phenyl O-(6-O-acetyl-2,3,4-tri-O-benzyl-α-D-glucopyranosyl)-(1->6)-2,3,4-tri-O-benzyl-1-thio-α-D-glucopyranoside (17).Crystalline O-(6-O-acetyl-2,3,4-tri-O-benzyl-α-D- glucopyranosyl)-(1->6)-2,3,4-tri-O-benzyl-β-D-glucopyranosyl chloride, readily obtainable in a stereospecific manner from 17 by treatment with chlorine, was used as the key glycosyl (isomaltosyl) donor in the bockwise synthesis of methyl glycosides of isomalto-oligosaccharides, up to and including the octasaccharide.The methyl α-glycoside of isomaltotetraose fluorinated at C-6 of the terminal D glucopyranosyl group was prepared by using SnCl2-activated 2,3,4-tri-O-benzyl-6-deoxy-6-fluoro-α,β-D-glucopyranosyl fluoride as the glycosyl donor, a suitably protected methyl α-isomaltotrioside as the nucleophile, and silver perchlorate as the promoter.The n.m.r. spectra (1H- and 13C-) of numereous synthetic intermediates were analyzed and completely assigned by a variety of two-dimensional homo- and hetero-nuclear n.m.r.-spectroscopic techniques, and the final deprotected title oligosaccharides were characterized by 13C-n.m.r. data.Silver perchlorate-mediated glycosylation reactions involving β-glycosyl chlorides were high-yielding and showed high stereoselectivity for the formation of an α-(cis)-glycosidic linkage.The practical limitation of obtaining high isomalto-oligosaccharides in this way appears to lie solely in the separation technique applied for the resolution of the crude products formed.
