- Five unusual natural carbohydrates from Actinosynnema pretiosum
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Five unusual hexose derivatives were isolated from the carbohydrate portion of the solid-state fermentation extract of Actinosynnema pretiosum ssp. auranticum ATCC 31565, which is a producing strain of maytansinoids that are a family of 19-membered macrocyclic lactams having extraordinary cytotoxic and antineoplastic activities. Their structures were determined to be 2-deoxy-α-D-arabino-hexopyranose (1), 2-deoxy-β-D-arabino- hexopyranose (2), 3,6-anhydro-2-deoxy-α-D-arabino-hexcofuranose (3), 3,6-anhydro-2-deoxy-β-D-arabino-hexofuranose (4), and 2-(D-glycerol-1,2- dihydroxyethyl)furan (5) by NMR spectroscopic experiments. Springer Science+Business Media, Inc. 2008.
- Lu, Chunhua,Bai, Linquan,Shen, Yuemao
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- INHIBITORS OF MALARIAL AND PLASMODIUM FALCIPARUM HEXOSE TRANSPORTER AND USES THEREOF
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Provided are molecules capable of binding to binding pockets of Plasmodium falciparum hexose transporter (PfHT) or analogs thereof and complexes comprising the same. Also provided herein are inhibitors of PfHT, pharmaceutical compositions comprising the i
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Paragraph 00520
(2021/08/14)
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- Organoboron-catalyzed regio- and stereoselective formation of β-2-deoxyglycosidic linkages
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A borinic acid derived catalyst enables regioselective and β-selective reactions of 2-deoxy- and 2,6-dideoxyglycosyl chloride donors with pyranoside-derived acceptors having unprotected cis-1,2- and 1,3-diol groups. The use of catalysis to promote a β-sel
- Beale, Thomas M.,Moon, Patrick J.,Taylor, Mark S.
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supporting information
p. 3604 - 3607
(2014/07/21)
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- NaBH3CN: A janus substitute for tin-free radical-based reactions
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Beside showing that thermal radical reactions (reduction, Giese reaction) are efficient if bromo-/iodosugars are treated with NaBH3CN and 2,2″-azobisisobutyronitrile, we explored new initiation conditions on the basis of CuI salts (≤0.5 equiv.) supposed to produce radicals from organobromides through a set. This was confirmed, as at about 50 C under an inert atmosphere acetobromoglucose was reduced to the rearranged 2-deoxyglucose and as N-allyl α-bromoamides reacted, depending on the conditions, either by reductive cyclization or atom-transfer radical cyclization. A related cyclization occurred upon using Cu(OAc)2. This and other assays showed the reduction by NaBH3CN of CuII salts, either added or formed in situ. Having both ionic and radical reactivity, NaBH 3CN appears as a Janus reagent that may be useful for tin-free radical chemistry under mild and very simple conditions. Copyright
- Guiard, Julie,Rahali, Yaniss,Praly, Jean-Pierre
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supporting information
p. 4461 - 4466
(2014/08/05)
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- NaBH3CN and other systems as substitutes of tin and silicon hydrides in the light or heat-initiated reduction of halosugars: A tunable access to either 2-deoxy sugars or 1,5-anhydro-itols
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UV light-promoted reduction of acetobromoglucose by NaBH3CN in t-BuOH afforded 1,3,4,6-tetra-O-acetyl-2-deoxy-α-d-arabino-hexopyranose in high yield and purity, via a Surzur-Tanner rearrangement, while, with 10 mol % thiophenol added, acetylated 1,5-anhydro-d-glucitol was cleanly obtained. Such tin-free and mild reductions, presumed to proceed via radical pathways, were more efficient with NaBH3CN compared to NaBH4 or NaBD 4, and do not occur with acetochloroglucose. Similar reductions to 1,3,4,6-tetra-O-acetyl-2-deoxy-α-d-arabino-hexopyranose were achieved upon heating to 80 C t-BuOH or CH3CN solutions of NaBH3CN and AIBN, but with a lower selectivity due to competing ionic reactions. With other pyranosyl bromides, reductions by NaBH3CN could be tuned similarly (d-galacto), but some (d-manno, 5-thio-d-xylo) gave mainly or exclusively 1,5-anhydro-itols. Other conditions, or reagents promoting SET process, afforded also reduced products, but with lower rates or selectivities. Primary iodides were reduced readily with NaBH3CN under UV light.
- Bruyère, Isabelle,Tóth, Zoltan,Benyahia, Hamida,Xue, Jia Lu,Praly, Jean-Pierre
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supporting information
p. 9656 - 9662
(2013/10/22)
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- Direct C-glycosylation of organotrifluoroborates with glycosyl fluorides and its application to the total synthesis of (+)-varitriol
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A mild, stereoselective, and quick approach to accessing alkynyl and alkenyl C-glycosides via BF3?Et2O promoted coupling of organotrifluoroborates and glycosyl fluorides is reported. The application of this method was further demonstrated by the concise and efficient total synthesis of (+)-varitriol in only seven steps.
- Zeng, Jing,Vedachalam, Seenuvasan,Xiang, Shaohua,Liu, Xue-Wei
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supporting information; experimental part
p. 42 - 45
(2011/03/22)
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- DABCO: An efficient promoter for the acetylation of carbohydrates and other substances under solvent-free conditions
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A simple, mild and efficient solvent-free method for the acetylation of carbohydrates, and their partially protected derivatives, as well as non-carbohydrate substances in excellent yields in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) is described with the advantage of tolerance to various functional groups, short reaction time and ease of product isolation.
- Ch, Ratnasekhar,Tyagi, Mohit,Patil, Premanand Ramrao,Kartha, K.P. Ravindranathan
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experimental part
p. 5841 - 5846
(2011/12/03)
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- Erosion of stereochemical control with increasing nucleophilicity: O-glycosylation at the diffusion limit
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(Chemical Equation Presented) Nucleophilic substitution reactions of 2-deoxyglycosyl donors indicated that the reactivity of the oxygen nucleophile has a significant impact on stereoselectivity. Employing ethanol as the nucleophile resulted in a 1:1 (α:β) ratio of diastereomers under SN1-like reaction conditions. Stereoselective formation of the 2-deoxy-α-O-glycoside was only observed when weaker nucleophiles, such as trifluoroethanol, were employed. The lack of stereoselectivity observed in reactions of common oxygen nucleophiles can be attributed to reaction rates of the stereochemistry-determining step that approach the diffusion limit. In this scenario, both faces of the prochiral oxocarbenium ion are subject to nucleophilic addition to afford a statistical mixture of diastereomeric products. Control experiments confirmed that all nucleophilic substitution reactions were performed under kinetic control.
- Beaver, Matthew G.,Woerpel
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supporting information; experimental part
p. 1107 - 1118
(2010/04/06)
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- Highly direct α-selective glycosylations of 3,4-o-carbonate-protected 2-deoxy-and 2,6-dideoxythioglycosides by preactivation protocol
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(Chemical Equation Presented) A new efficient pre-activation method for the highly α-stereoselective glycosylation of 2-deoxysugars and 2,6-dideoxysugars has been developed using 2-deoxy- and 2,6- dideoxythioglycosides as glycosyl donors. The approach allows a wide range of glycosyl acceptors and donors to be used; the α-selectivity is very good to excellent.
- Lu, Yin-Suo,Li, Qin,Zhang, Li-He,Ye, Xin-Shan
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supporting information; experimental part
p. 3445 - 3448
(2009/05/07)
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- Towards α- or β-D-C-glycosyl compounds by tin-catalyzed addition of glycosyl radicals to acrylonitrile and vinylphosphonate, and flexible reduction of tetra-O-acetyl-α-D-glucopyranosyl bromide with cyanoborohydride
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Photo-induced radical addition of acetylated α-D-glucopyranosyl bromide (1) to acrylonitrile or diethyl vinylphosphonate, in the presence of catalytic amounts of tri-n-butyltin chloride and sodium (or tetra-n-butylammonium) cyanoborohydride in excess, all
- Praly, Jean-Pierre,Ardakani, Azin Salek,Bruyere, Isabelle,Marie-Luce, Chrystelle,Bing Qin, Bing
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p. 1623 - 1632
(2007/10/03)
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- A method for obtaining equilibrium tautomeric mixtures of reducing sugars via glycosylamines using nonaqueous media
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Equilibrium tautomeric mixtures of several mono- and disaccharides are obtained in anhydrous form, without the use of water, by reacting the commercially available reducing sugars with ammonia gas in dry methanol, followed by the concentration of the resultant solution to dryness. Mutarotation and hydrolysis of the initially formed glycosylamine in the resultant medium account for the transformation. Equilibrium anomeric mixtures enriched in the β-form of commercially available sugars such as α-D-glucose and α-lactose have not only vastly increased solubility, but are also synthetically valuable as these can be readily converted to the methyl/benzyl/trimethylsilyl ether and other derivatives for further transformations.
- Allavudeen, Sikkander Sulthan,Kuberan, Balagurunathan,Loganathan, Duraikkannu
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p. 965 - 968
(2007/10/03)
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- C-Glycosylation of tri-O-benzyl-2-deoxy-D-glucose: Synthesis of naphthyl-substituted 3,6-dioxabicyclo[3.2.2]nonanes
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The syntheses of naphthol 7, naphthol 8, naphthol 11 and naphthol 12 are described, starting from juglone 13. C-Glycosylation of naphthol 8 with benzyl-protected glycosyl donor 10 using trimethylsilyl trifluoromethanesulfonate and silver perchlorate or boron trifluoride-diethyl ether affords rearranged product 36 in which the glycosyl donor has undergone an unusual 1,6-hydride shift. Use of the corresponding naphthol 12 as the glycosyl acceptor under the same conditions affords the expected C-glycoside 34. Use of the naphthol 7 and naphthol 11 affords predominantly rearranged products 35 and 37 respectively, albeit in much lower yield than the reactions using the corresponding bromonaphthols. The study described herein establishes that introduction of an acetyl group to C-3, as in C-glycosylnaphthoquinone 4, as required for conversion to analogues of medermycin 1 such as 3, necessitates that the C-glycosylation step be effected before regioselective introduction of the acetyl group.
- Brimble,Brenstrum
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p. 1612 - 1623
(2007/10/03)
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- Radical dimerization of glycosyl 2-pyridylsulfones with samarium (II) iodide in the presence of HMPA
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Reduction of glycosyl 2-pyridylsulfones by samarium (II) iodide in the presence of HMPA leads to glycosyl dimers in up to 74% yield. This is rationalized by a free-radical mechanism.
- Doisneau, Gilles,Beau, Jean-Marie
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p. 3477 - 3480
(2007/10/03)
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- Reactivity of glucosyl radical in the presence of phenols
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Glucosyl radicals from the photoreaction of α-bromo-2,3,4,6-tetra-O-acetylglucose (ABG) with hexabutylditin react with phenols. 4-H3-COC6H4O· was identified by means of EPR spectroscopy in the case of 4-methoxyphenol, and the corresponding α-O-glucoside was isolated along with 1- and 2-deoxysugars and the dimers of glucosyl radical. The present results are consistent with the formation of α-O-glucosides observed in the electrochemical reaction of ABG and phenols, although in this case the dimers represent the main reaction products.
- Alberti, Angelo,Della Bona, Maria A.,Macciantelli, Dante,Pelizzoni, Francesca,Sello, Guido,Torri, Giangiacomo,Vismara, Elena
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p. 10241 - 10248
(2007/10/03)
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- Synthesis of α-(1->2)-, α-(1->3)-, α-(1->4)-, and α-(1->5)-C-Linked Disaccharides through 2,3,4,6-Tetra-O-acetylglucopyranosyl Radical Additions to 3-Methylidene-7-oxabicycloheptan-2-one Derivatives
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The "naked sugar" (+)-1 (1R,2S,4R)-2-cyano-7-oxabicyclohept-5-en-2-yl (1S')-camphanate) has been converted into (+)-(1R,4R,5R,6R)-3-methylidene-5-exo,6-exo-(isopropylidenedioxy)-7-oxabicycloheptan-2-one ((+)-3) and (-)-(1S,4R,5R,6R)-5-exo-(b
- Bimwala, R. Mampuya,Vogel, Pierre
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p. 2076 - 2083
(2007/10/02)
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