1824-94-8Relevant articles and documents
Temporary Protection and Activation in the Regioselective Synthesis of Saccharide Sulfates
Langston, Steven,Bernet, Bruno,Vasella, Andrea
, p. 2341 - 2353 (1994)
Regioselective sulfation with Et3N*SO3 of partially protected or unprotected glycosides via stannanediyl acetals or stannyl ethers, combined with persistent or temporary protecting groups is described.Stannylation of phenylboronates, followed by sulfation and aqueous workup, is an efficient way for the synthesis of monosulfated monosaccharides.The stannanediyl acetal 2 led in high yields to 3a, while sulfation of the diol 1 proceeded more slowly and led in lower yield to a mixture 1/3a/4a/5a (Scheme 1).The trehalose disulfate 8a was obtained in high yields from 7; reducing the amount of sulfating agent led to a mixture 6/8a/9a.Stannylation and sulfation of the galactoside 11 afforded 13a, while direct sulfation of 11 gave a mixture of the 2- and 3-sulfates 13a/14a besides some disulfate 15a.Sulfation of the lactose derivative 16 and the stannanediyl acetal 17 gave the 3-sulfate 18a, with some disulfate 19a being formed from 16.The mannopyranoside 21 was selectively sulfated at OH-C(2), leading to 22a, while the corresponding diol 20 yielded mostly the isomer 23a and some disulfate 24a.Sulfation of the stannyl ethers derived from the gluco- and galactopyranosides 25 and 28 and (Bu3Sn)2O afforded high yields of the 2,6-disulfate 26a and the 3,6-disulfate 29a, respectively.Stannylation of 25 and 28 with Bu2SnO and sulfation proceeded less satisfactorily.Stannylation of the phenylboronate 32 (Bu2SnO) and sulfation gave good yields of the 2-sulfate 27a; stannylation and benzoylation yielded the 2-benzoate 34 (Scheme 2).Similarly, the galactose-derived 37 provided high yields of the 3-sulfate 30a and of the 3-benzoate 39.Direct sulfation of the phenylboronates 32 and 37 proceeded in lower yields and gave mixtures.
Operationally simple and efficient workup procedure for TBAF-mediated desilylation: Application to halichondrin synthesis
Kaburagi, Yosuke,Kishi, Yoshito
, p. 723 - 726 (2007)
An operationally simple and efficient workup method for tetrabutylammonium fluoride (TBAF)-mediated t-butyldimethylsilyl (TBS) deprotection has been developed. The procedure includes addition of a sulfonic acid resin and calcium carbonate, followed by filtration and evaporation. This method eliminates the tedious aqueous-phase extraction process to remove excess TBAF and materials derived from TBAF, thereby making the protocol highly amenable to multiple TBS deprotections. Its efficiency and usefulness were demonstrated by using the transformation of 1 a to 3a in the halichondrin synthesis.
Preliminary 1H NMR investigation of sialic acid transfer by the trans-sialidase from Trypanosoma cruzi
Wilson, Jennifer C,Kiefel, Milton J,Albouz-Abo, Samia,Von Itzstein, Mark
, p. 2791 - 2794 (2000)
1H NMR spectroscopy has been used to investigate the transfer of sialic acid from sialic acid donor molecules to acceptor molecules using the trans-sialidase from Typanosoma cruzi. It is clearly demonstrated that NMR spectroscopy is an efficien
STEROIDAL ALKALOIDS FROM SOLANUM CAPSICASTRUM
Lin, Chun-Nan,Chung, Mei-Ing,Lin, Son-Yuan
, p. 305 - 308 (1987)
From the rootbark of Solanum capsicastrum, in addition to etioline and isoteinemine, a new 22,26-epiminocholestene glycoside named capsicastrine was isolated and its structure elucidated as isoteinemine O(3)-β-D-galactopyranoside by physical and chemical
Catalytic Consequences of Experimantal Evolution. Part 1. Catalysis by the Wild-type Second β-Galactosidase (ebg0) of Escherichia coli: a Comparison with the lacZ Enzyme
Burton, John,Sinnott, Michael L.
, p. 359 - 364 (1983)
β-D-Galactopyranose is the initial product of the hydrolysis of β-D-galactopyranosyl fluoride by ebg0 enzyme.Transfer to methanol of a β-D-galactopyranosyl residue from either m-nitrophenol or 3-bromopyridine is seven times more favourable than
Three new glycosides from the whole plant of Clematis lasiandra Maxim and their cytotoxicity
Tian, Xiang-Rong,Feng, Jun-Tao,Ma, Zhi-Qing,Xie, Na,Zhang, Jing,Zhang, Xing,Tang, Hai-Feng
, p. 168 - 172 (2014)
Phytochemical investigation on the whole plant of Clematis lasiandra Maxim led to the isolation of two new phenolic glycosides (1 and 2), one new lignanoid glycoside (3), together with three known lignanoid glycosides (4-6). The structures of the new comp
Carbon glycoside glycosylated tetravalent platinum compound as well as synthesis method and application thereof
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Paragraph 0064-0067, (2021/07/08)
The invention provides a carbon glycoside glycosylated tetravalent platinum compound, a synthesis method and application thereof. R1 and R2 are independently C1-C4 lower alkanes, R3 is glucose, galactose, mannose and ribose, different sugars are used as raw materials, and a series of carbon glycoside glycosylated tetravalent platinum compounds are synthesized through protection and deprotection reaction and metallization reaction of the sugars. The synthesis method is simple, the used raw materials are cheap and easy to obtain, the glycosylated tetravalent platinum compound has the capacity of targeting glucose transporter protein and has potential application value in the field of cancer treatment, introduction of a C-glucosidic bond enables the series of compounds to have the capacity of resisting hydrolysis of beta-glucosidase, and the compound is expected to be applied to the field of oral antitumor drugs.
Calixanthomycin A: Asymmetric Total Synthesis and Structural Determination
Chen, Kuanwei,Xie, Tao,Shen, Yanfang,He, Haibing,Zhao, Xiaoli,Gao, Shuanhu
supporting information, p. 1769 - 1774 (2021/03/08)
We report the first asymmetric total synthesis and structural determination of calixanthomycin A. Taking advantage of a modular strategy, a concise approach was developed to assemble the hexacyclic skeleton with both enantiomers of the lactone A ring. Stereoselective glycosylation coupled the angular hexacyclic framework with a monosaccharide fragment to produce calixanthomycin A and its stereoisomers. This enable us to determine and assign the absolute configuration of C-25 (25S) and monosaccharide (derivative of l-glucose).
Structure of the unusual Sinorhizobium fredii HH103 lipopolysaccharide and its role in symbiosis
Di Lorenzo, Flaviana,Speciale, Immacolata,Silipo, Alba,Alías-Villegas, Cynthia,Acosta-Jurado, Sebastián,Rodríguez-Carvajal, Miguel-ángel,Dardanelli, Marta S.,Palmigiano, Angelo,Garozzo, Domenico,Ruiz-Sainz, José-Enrique,Molinaro, Antonio,Vinardell, José-María
, p. 10969 - 10987 (2021/01/07)
Rhizobia are soil bacteria that form important symbiotic associations with legumes, and rhizobial surface polysaccharides, such as K-antigen polysaccharide (KPS) and lipopolysaccharide (LPS), might be important for symbiosis. Previously, we obtained a mutant of Sinorhizobium fredii HH103, rkpA, that does not produce KPS, a homopolysaccharide of a pseudaminic acid derivative, but whose LPS electrophoretic profile was indistinguishable from that of the WT strain. We also previously demonstrated that the HH103 rkpLMNOPQ operon is responsible for 5-acetamido-3,5,7,9-tetradeoxy-7-(3-hydroxybutyramido)-L-glyc-ero-L-manno-nonulosonic acid [Pse5NAc7(3OHBu)] production and is involved in HH103 KPS and LPS biosynthesis and that an HH103 rkpM mutant cannot produce KPS and displays an altered LPS structure. Here, we analyzed the LPS structure of HH103 rkpA, focusing on the carbohydrate portion, and found that it contains a highly heterogeneous lipid A and a peculiar core oligosaccharide composed of an unusually high number of hexuronic acids containing b-configured Pse5NAc7(3OHBu). This pseudaminic acid derivative, in its a-configuration, was the only structural component of the S. fredii HH103 KPS and, to the best of our knowledge, has never been reported from any other rhizobial LPS. We also show that Pse5NAc7(3OHBu) is the complete or partial epitope for a mAb, NB6-228.22, that can recognize the HH103 LPS, but not those of most of the S. fredii strains tested here. We also show that the LPS from HH103 rkpM is identical to that of HH103 rkpA but devoid of any Pse5NAc7(3OHBu) residues. Notably, this rkpM mutant was severely impaired in symbiosis with its host, Macroptilium atropurpureum.
Chemical constituents of the aerial parts of Algerian Galium brunneum: Isolation of new hydroperoxy sterol glucosyl derivatives
Bertella, Anis,Bitam, Fatma,Carbone, Marianna,Ciavatta, Maria Letizia,Gavagnin, Margherita,Smadi, Abla
, p. 39 - 45 (2020/05/25)
The liposoluble extract of Galium brunneum aerial parts from North-eastern Algeria was chemically investigated. The EtOAc soluble portion contained a series of glycosyl cucurbitacins and sterols including three new glucosyl hydroperoxy sterols 1–3 among other phenolic components whereas the BuOH soluble fraction was dominated by glycosyl derivatives of flavonoids, iridoids and lignans, according to the chemistry reported in the literature for the genus Galium. The structure of new oxidized sterols 1–3 was determined by spectroscopic methods as well as by comparison with related known metabolites. Selected main compounds from both extracts, which revealed moderate antibacterial activities, were tested for their growth inhibitory properties against Gram-positive and Gram-negative bacteria. This is the first report of cucurbitacins in plants of genus Galium.
