- Substrate Substitution in Kanosamine Biosynthesis Using Phosphonates and Phosphite Rescue
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Kanosamine is an antibiotic and antifungal compound synthesized from glucose 6-phosphate (G6P) inBacillus subtilisby the action of three enzymes: NtdC, which catalyzes NAD-dependent oxidation of the C3-hydroxyl; NtdA, a PLP-dependent aminotransferase; and
- Palmer, David R. J.,Vetter, Natasha D.
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p. 1926 - 1932
(2021/06/28)
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- Synthesis of methyl 4,6-di-o-ethyl-α-d-glucopyranoside-based azacrown ethers and their effects in asymmetric reactions
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Carbohydrate-based crown ethers have been reported to be able to generate asymmetric induction in certain reactions. Previously, it was proved that the monosaccharide unit, the anomeric substituent, and the sidearm could influence the catalytic activity of the monoaza-15-crown-5 macrocycles derived from sugars. In order to gain information about the effect of the flexibility, 4,6-di-O-ethyl-glucoside-based crown compounds were synthesized, and their efficiency was compared to the 4,6-O-benzylidene analogues. It was found that the absence of the two-ring annulation has a negative effect on the enantioselectivity in liquid-liquid two-phase reactions: in the Darzens condensation of 2-chloroacetophenone and in the epoxidation of chalcone. The same trend was observed in the solid-liquid phase Michael addition of diethyl acetamidomalonate. Surprisingly, in the solid-liquid phase cyclopropanation of benzylidenemalononitrile, one of the new catalysts was highly enantioselective (99% ee).
- Bagi, Péter,Bakó, Péter,Heged?s, László,Orbán, István,Rapi, Zsolt,Varga, Bertalan
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- Triethylamine-methanol mediated selective removal of oxophenylacetyl ester in saccharides
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A highly selective, mild, and efficient method for the cleavage of oxophenylacetyl ester protected saccharides was developed using triethylamine in methanol at room temperature. The reagent proved successful against different labile groups like acetal, ketal, and PMB and also generated good yields of the desired saccharides bearing lipid esters. Further, we also observed DBU in methanol as an alternative reagent for the deprotection of acetyl, benzoyl, and oxophenylacetyl ester groups. This journal is
- Rasool, Javeed Ur,Kumar, Atul,Ali, Asif,Ahmed, Qazi Naveed
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supporting information
p. 338 - 347
(2021/01/29)
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- Automated Quantification of Hydroxyl Reactivities: Prediction of Glycosylation Reactions
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The stereoselectivity and yield in glycosylation reactions are paramount but unpredictable. We have developed a database of acceptor nucleophilic constants (Aka) to quantify the nucleophilicity of hydroxyl groups in glycosylation influenced by the steric, electronic and structural effects, providing a connection between experiments and computer algorithms. The subtle reactivity differences among the hydroxyl groups on various carbohydrate molecules can be defined by Aka, which is easily accessible by a simple and convenient automation system to assure high reproducibility and accuracy. A diverse range of glycosylation donors and acceptors with well-defined reactivity and promoters were organized and processed by the designed software program “GlycoComputer” for prediction of glycosylation reactions without involving sophisticated computational processing. The importance of Aka was further verified by random forest algorithm, and the applicability was tested by the synthesis of a Lewis A skeleton to show that the stereoselectivity and yield can be accurately estimated.
- Chang, Chun-Wei,Lin, Mei-Huei,Chan, Chieh-Kai,Su, Kuan-Yu,Wu, Chia-Hui,Lo, Wei-Chih,Lam, Sarah,Cheng, Yu-Ting,Liao, Pin-Hsuan,Wong, Chi-Huey,Wang, Cheng-Chung
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p. 12413 - 12423
(2021/05/03)
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- How do Various Reaction Parameters Influence Anomeric Selectivity in Chemical Glycosylation with Thioglycosides and NIS/TfOH Activation?
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The reaction of glycosyl donor phenyl 2,3,4,6-tetra-O-benzyl-1-thio-β-D-glucopyranoside with NIS/TfOH(cat.) was systematically studied under various reaction conditions. Neither the molecular sieve pore size nor amount of NIS activator was found to have a
- Andersen, Sofie M.,Heuckendorff, Mads,Jensen, Henrik H.,Trinderup, Helle H.
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p. 3251 - 3259
(2021/06/25)
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- Carbocyclic Substrate Analogues Reveal Kanosamine Biosynthesis Begins with the α-Anomer of Glucose 6-Phosphate
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NtdC is an NAD-dependent dehydrogenase that catalyzes the conversion of glucose 6-phosphate (G6P) to 3-oxo-glucose 6-phosphate (3oG6P), the first step in kanosamine biosynthesis in Bacillus subtilis and other closely-related bacteria. The NtdC-catalyzed r
- Vetter, Natasha D.,Jagdhane, Rajendra C.,Richter, Brett J.,Palmer, David R. J.
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p. 2205 - 2211
(2020/09/01)
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- Stereoselective Phenylselenoglycosylation of Glycals Bearing a Fused Carbonate Moiety toward the Synthesis of 2-Deoxy-β-galactosides and β-Mannosides
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A phenylselenoglycosylation reaction of glycal derivatives mediated by diphenyl diselenide and phenyliodine(III) bis(trifluoroacetate) under mild conditions is described. Stereoselective glycosylation has been achieved by installing fused carbonate on those glycals. 3,4-O-Carbonate galactals and 2,3-O-carbonate 2-hydroxyglucals are converted into corresponding glycosides in good yields with excellent β-selectivity, resulting in 2-phenylseleno-2-deoxy-β-galactosides and 2-phenylseleno-β-mannosides which are good precursors of 2-deoxy-β-galactosides and β-mannosides, respectively.
- Li, Zhongjun,Meng, Shuai,Yao, Wang,Zhong, Wenhe
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supporting information
(2020/04/09)
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- Mapping mechanisms in glycosylation reactions with donor reactivity: Avoiding generation of side products
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The glycosylation reaction, which is key for the studies on glycoscience, is challenging due to its complexity and intrinsic side reactions. Thioglycoside is one of the most widely used glycosyl donors in the synthesis of complex oligosaccharides. However, one of the challenges is its side reactions, which lower its yield and limits its efficiency, thereby requiring considerable effort in the optimization process. Herein, we reported a multifaceted experimental approach that reveals the behaviors of side reactions, such as the intermolecular thioaglycon transformation and N-glycosyl succinimides, via the glycosyl intermediate. Our mechanistic proposal was supported by low temperature NMR studies that can further be mapped by utilizing relative reactivity values. Accordingly, we also presented our findings to suppress the generation of side products in solving this particular problem for achieving high-yield glycosylation reactions.
- Wang, Cheng-Chung,Chang, Chun-Wei,Lin, Mei-Huei,Wu, Chia-Hui,Chiang, Tsun-Yi
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p. 15945 - 15963
(2021/01/18)
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- Dehydrative Glycosylation Enabled by a Comproportionation Reaction of 2-Aryl-1,3-dithiane 1-Oxide?
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A new dehydrative glycosylation reaction has been established by capitalizing on the comproportionation reaction of 2-aryl-1,3-dithiane 1-oxides promoted by triflic anhydride (Tf2O). By wedding the high potency of thiophilic promoter system with the step efficiency of dehydrative glycosylation, this reagent underwent facile intermolecular oxothio acetalization with C1-hemiacetal donor to install a temporary leaving group, rendering a transient electrophilic center at the remote site to the anomeric position. The sulfenyl triflate tethered at the terminus concomitantly activated the sulfide intramolecularly to afford the oxocarbenium ion, thereby facilitating the title glycosylation. Aside from accommodating broad range functional groups and inactive hemiacetal substrates, the present activation protocol also proved expedient for 1,3-diol protection. Most importantly, this method further provided a fresh perspective for the application of sulfur chemistry to carbohydrate chemistry.
- Cai, Lei,Zeng, Jing,Li, Ting,Xiao, Ying,Ma, Xiang,Xiao, Xiong,Zhang, Qin,Meng, Lingkui,Wan, Qian
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- Assessing the Optimal Deoxygenation Pattern of Dodecyl Glycosides for Antimicrobial Activity Against Bacillus anthracis
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The discovery of the bactericide dodecyl 2,6-dideoxypyranoside reorganizing membrane phospholipid matrix of Bacillus species into a hexagonal phase, encouraged further research on glycone deoxygenation/bioactivity relationship. We now describe expedient syntheses of new 2-, 3-, 4-deoxy, 2,3- and 3,4-dideoxy glycosides in moderate to good yields. Interestingly, Amberlyst 15 is a key protagonist, efficiently applied for the transacetalation of alkyl deoxy glycosides and for ring contraction to access regioselectively hexofuranosides. The 2-deoxy-d-arabino pyranoside affords the higher MIC values against two Bacillus spp. and Enterococcus faecalis, while a 4-fold decrease or higher was found by inversion of configuration or by deoxygenation at C-3. While 2,3- and 3,4-dideoxygenation do not improve bioactivity, the 4,6-dideoxy-α-d-xylo-hexopyranoside remains a promising glycoside, presenting low MIC values for all species tested, and low cytotoxicity in intestinal and liver cell models.
- Dias, Catarina,Martins, Alice,Pelerito, Ana,Oliveira, Maria C.,Contino, Marialessandra,Colabufo, Nicola A.,Rauter, Amélia P.
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p. 2224 - 2233
(2019/02/19)
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- Establishment of Guidelines for the Control of Glycosylation Reactions and Intermediates by Quantitative Assessment of Reactivity
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Stereocontrolled chemical glycosylation remains a major challenge despite vast efforts reported over many decades and so far still mainly relies on trial and error. Now it is shown that the relative reactivity value (RRV) of thioglycosides is an indicator for revealing stereoselectivities according to four types of acceptors. Mechanistic studies show that the reaction is dominated by two distinct intermediates: glycosyl triflates and glycosyl halides from N-halosuccinimide (NXS)/TfOH. The formation of glycosyl halide is highly correlated with the production of α-glycoside. These findings enable glycosylation reactions to be foreseen by using RRVs as an α/β-selectivity indicator and guidelines and rules to be developed for stereocontrolled glycosylation.
- Chang, Chun-Wei,Wu, Chia-Hui,Lin, Mei-Huei,Liao, Pin-Hsuan,Chang, Chun-Chi,Chuang, Hsiao-Han,Lin, Su-Ching,Lam, Sarah,Verma, Ved Prakash,Hsu, Chao-Ping,Wang, Cheng-Chung
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p. 16775 - 16779
(2019/11/03)
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- Anti-coagulation pentasaccharide and preparing method and medical application thereof
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The invention relates to a synthesized pentasaccharide compound, salt thereof, and application of the pentasaccharide compound in preparing medicines for preventing and/or treating blood coagulation disorder related diseases.
- -
-
Paragraph 0110; 0124-0126; 0130-0131
(2019/01/23)
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- Stereoselective β-mannosylation via anomeric O-Alkylation: Concise synthesis of β-D-Xyl-(l→2)-β-D-Man-(1→4)-α-D-Glc-OMe, a trisaccharide oligomer of the hyriopsis schlegelii glycosphingolipid
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Synthesis of ?-D-Xyl-(l→2)-?-D-Man-(1→4)-α-D-Glc-OMe (1), a trisaccharide oligomer of the Hyriopsis schlegelii glycosphingolipid is described. The synthesis involves a key ?-mannosylation via cesium carbonate-mediated anomeric O-alkylation for direct synt
- Bhetuwal, Bishwa Raj,Woodward, Justin,Li, Xiaohua,Zhu, Jianglong
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p. 162 - 172
(2017/11/20)
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- Co2(CO)6-propargyl cation mediates glycosylation reaction by using thioglycoside
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We discovered that the cobalt-propargyl cation can mediate the glycosylation reaction by activating the thioglycoside donor. The glyco-oxacarbenium cation was formed by transferring the thio-aglycone to the cobalt-propargyl cation that was generated from the cobalt-propargylated acceptor in situ via the activating with Lewis acid. The reactivity of the donor (Armed or dis-armed) and the amount of the Lewis acid control the releasing rate of the cobalt-propargyl group.
- Xia, Meng-jie,Yao, Wang,Meng, Xiang-bao,Lou, Qing-hua,Li, Zhong-jun
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supporting information
p. 2389 - 2392
(2017/05/29)
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- Synthesis of MeON-neoglycosides of digoxigenin with 6-deoxy- and 2,6-dideoxy-D-glucose derivatives and their anticancer activity
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Cardiac glycosides show anticancer activities and their deoxy-sugar chains are vital for their anticancer effects. In order to study the structure-activity relationship (SAR) of cardiac glycosides toward cancers and get more potent anticancer agents, a series of MeON-neoglycosides of digoxigenin was synthesized and evaluated. First, ten 6-deoxy- and 2,6-dideoxy-D-glucopyranosyl donors were synthesized starting from methyl α-D-glucopyranoside and 2-deoxy-D-glucose. Meanwhile, the digoxigenin was obtained by acidic hydrolysis of commercially available digoxin as glycosyl acceptor. Then, a 22-member MeON-neoglycoside library of digoxigenin was successfully synthesized by neoglycosylation method. Finally, the induction of Nur77 expression and its translocation from the nucleus to cytoplasm together with cytotoxicity of these MeON-neoglycosides were evaluated. The SAR analysis revealed that C3 glycosylation is required for their induction of Nur77 expression. Moreover, some MeON-neoglycosides (2b and 8b) could significant induce the expression of Nur77 and its translocation from the nucleus to cytoplasm. However, these compounds showed no inhibitory effects on the proliferation of cancer cells, suggesting that they may not induce apoptosis of NIH-H460 cancer cells and their underlying potential and application toward cancer cells deserves future study.
- Wang, Dong-dong,Li, Xiao-san,Bao, Yu-zhou,Liu, Jie,Zhang, Xiao-kun,Yao, Xin-sheng,Sun, Xue-Long,Tang, Jin-Shan
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supporting information
p. 3359 - 3364
(2017/07/07)
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- Synthesis and binding affinity analysis of α1-2- and α1-6-O/S-linked dimannosides for the elucidation of sulfur in glycosidic bonds using quartz crystal microbalance sensors
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The role of sulfur in glycosidic bonds has been evaluated using quartz crystal microbalance methodology. Synthetic routes towards α1-2- and α1-6-linked dimannosides with S- or O-glycosidic bonds have been developed, and the recognition properties assessed in competition binding assays with the cognate lectin concanavalin A. Mannose-presenting QCM sensors were produced using photoinitiated, nitrene-mediated immobilization methods, and the subsequent binding study was performed in an automated flow-through instrumentation, and correlated with data from isothermal titration calorimetry. The recorded Kd-values corresponded well with reported binding affinities for the O-linked dimannosides with affinities for the α1-2-linked dimannosides in the lower micromolar range. The S-linked analogs showed slightly disparate effects, where the α1-6-linked analog showed weaker affinity than the O-linked dimannoside, as well as positive apparent cooperativity, whereas the α1-2-analog displayed very similar binding compared to the O-linked structure.
- Norberg, Oscar,Wu, Bin,Thota, Niranjan,Ge, Jian-Tao,Fauquet, Germain,Saur, Ann-Kathrin,Aastrup, Teodor,Dong, Hai,Yan, Mingdi,Ramstr?m, Olof
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supporting information
p. 35 - 42
(2017/10/25)
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- A green and convenient method for regioselective mono and multiple benzoylation of diols and polyols
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An efficient method for regioselective benzoylation of diols and polyols was developed. The benzoylation is catalyzed by only 0.2 equiv of benzoate anion in acetonitrile with the addition of a stoichiometric amount of benzoic anhydride under very mild condition, leading to high yields. Compared with all other methods, this method shows particular advantage in regioselective multiple benzoylation of polyols, and in avoiding the use of any metal-based catalysts and any amine bases, which is more environment-friendly.
- Zhang, Xiaoling,Ren, Bo,Ge, Jiantao,Pei, Zhichao,Dong, Hai
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supporting information
p. 1005 - 1010
(2016/02/03)
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- A Synthetic Toolbox for the In Situ Formation of Functionalized Homo- and Heteropolysaccharide-Based Hydrogel Libraries
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A synthetic toolbox for the introduction of aldehydo and hydrazido groups into the polysaccharides hyaluronic acid, alginate, dextran, pullulan, glycogen, and carboxymethyl cellulose and their use for hydrogel formation is reported. Upon mixing differently functionalized polysaccharides derived from the same natural precursor, hydrazone cross-linking takes place, which results in formation of a hydrogel composed of one type of polysaccharide backbone. Likewise, hydrogels based on two different polysaccharide strands can be formed after mixing the corresponding aldehydo- and hydrazido-modified polysaccharides. A second line of these studies paves the way to introduce a biomedically relevant ligand, namely, the adhesion factor cyclic RGD pentapeptide, by using an orthogonal click reaction. This set of modified polysaccharides served to create a library of hydrogels that differ in the combination of polysaccharide strands and the degree of cross-linking. The different hydrogels were evaluated with respect to their rheological properties, their ability to absorb water, and their cytotoxicity towards human fibroblast cell cultures. None of the hydrogels studied were cytotoxic, and, hence, they are in principal biocompatible for applications in tissue engineering.
- Dibbert, Nick,Krause, Andreas,Rios-Camacho, Julio-Cesar,Gruh, Ina,Kirschning, Andreas,Dr?ger, Gerald
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supporting information
p. 18777 - 18786
(2016/12/26)
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- Four Different Regioisomeric Polycarbonates Derived from One Natural Product, d -Glucose
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Strategies for the preparation of polycarbonates, derived from the natural product d-glucose, which have the potential to degrade back into their bioresorbable starting material and CO2, were developed. By employing established carbohydrate pro
- Lonnecker, Alexander T.,Lim, Young H.,Felder, Simcha E.,Besset, Céline J.,Wooley, Karen L.
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p. 7857 - 7867
(2016/11/09)
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- Stable analogues of nojirimycin-synthesis and biological evaluation of nojiristegine and manno-nojiristegine
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Two novel iminosugars called nojiristegines, being structural hybrids between nor-tropane alkaloid calystegine and nojirimycins, have been synthesised and found to be stable molecules despite the presence of a hemiaminal functionality. The synthesised iminosugars were evaluated against a panel of glycosidases and the best inhibition (IC50), found against α-glucosidases, was in the micromolar region. The compounds were also evaluated as potential antibiotics but no useful level of activity was observed.
- Viuff, Agnete H.,Besenbacher, Louise M.,Kamori, Akiko,Jensen, Mikkel T.,Kilian, Mogens,Kato, Atsushi,Jensen, Henrik H.
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supporting information
p. 9637 - 9658
(2015/09/28)
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- Glycoporphyrin Catalysts for Efficient C-H Bond Aminations by Organic Azides
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We report herein the synthesis of new glycoporphyrin ligands which bear a glucopyranoside derivative on each meso-aryl moiety of the porphyrin skeleton. The saccharide unit is directly conjugated to the porphyrin or a triazole spacer is placed between the carbohydrate and porphyrin ring. The obtained glycoporphyrin ligands were employed to synthesize cobalt(II), ruthenium(II), and iron(III) complexes which were tested as catalysts of C-H bond aminations by organic azides. Two of the synthesized complexes were very efficient in promoting catalytic reactions, and the results achieved indicated that ruthenium and iron complexes show an interesting complementary catalytic activity in several amination reactions. The eco-friendly iron catalyst displayed very good chemical stability in catalyzing the amination reaction for three consecutive runs without losing catalytic activity. (Chemical Equation Presented).
- Tseberlidis, Giorgio,Zardi, Paolo,Caselli, Alessandro,Cancogni, Damiano,Fusari, Matteo,Lay, Luigi,Gallo, Emma
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supporting information
p. 3774 - 3781
(2015/08/19)
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- Enhanced basicity of Ag2O by coordination to soft anions
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In Ag2O-mediated benzylation, the addition of a catalytic amount of KI can greatly improve reactivity. This is usually attributed to the formation of a more reactive iodo-substituted electrophile. However, our studies show this to be due to the enhanced basicity of Ag2O through coordination of soft iodide anions to the silver atom, and show KI to be an initiator. A catalytic amount of Ag2O and NaBr can catalyze transesterification reactions, indicating the enhanced basicity of Ag2O by bromide. We believe that this is a general effect for metal oxides and soft anions, applicable to a wider range of organic reaction systems. All your base belongs to us: In Ag2O-mediated benzylation, the addition of a catalytic amount of KI can greatly improve reactivity. Our studies show this to be attributable to the enhanced basicity of Ag2O through coordination of soft iodide anions to the silver atom, and show KI to be an initiator. Thus, NaBr as an initiator combined with Ag2O has been successfully used to catalyze transesterification reactions.
- Ren, Bo,Wang, Meiyan,Liu, Jingyao,Ge, Jiantao,Dong, Hai
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p. 761 - 765
(2015/03/04)
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- Exploring glycosylation reactions under continuous-flow conditions
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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.
- Cancogni, Damiano,Lay, Luigi
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supporting information
p. 2873 - 2878
(2015/01/16)
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- Linearization of carbohydrate derived polycyclic frameworks
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We report easy access to carbohydrate derived diverse tricyclic skeletons which could be beneficial for exploring polyfunctionalized chiral alicycles. The key reaction to assemble a sugar fused tricyclic core is intermolecular tandem esterification and 1,3-dipolar cycloaddition. The framework was elaborated using amide forming reactions, opening of isoxazolidine rings followed by N and O-acylations. The sequences provide distinct, spatially separated and encoded chemical entities that may pave the way to investigate cell functions.
- Singh, Priyanka,Panda, Gautam
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p. 31892 - 31903
(2014/08/18)
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- Click chemistry route to tricyclic monosaccharide triazole hybrids: Design and synthesis of substituted hexahydro-4H-pyrano[2,3-f][1,2,3]triazolo[5,1-c][1,4]oxazepines
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A click chemistry approach to novel tricyclic monosaccharide triazole hybrids, namely, aryl substituted hexahydro-4H-pyrano[2,3-f][1,2,3]triazolo[5,1-c][1,4]oxazepine derivatives from an intramolecular 1,3-dipolar cycloaddition of 6-azido-4-O-propargyl glycopyranosides has been reported.
- Konda, Saidulu,Rao, Pallavi,Oruganti, Srinivas
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p. 63962 - 63965
(2015/02/19)
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- Hydrophobic and hydrophilic balance and its effect on mesophase behaviour in hydroxyalkyl ethers of methyl glucopyranoside
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Four series of monosubstituted methyl a-d-glucopyranoside hydroxyal- kyl ethers were prepared and their thermotropic and lyotropic self-organising properties were investigated in terms of the hydrophobic-hydrophilic balance with respect to their molecular
- Singh, Madan K.,Xu, Rui,Moebs, Sylvie,Kumar, Anil,Queneau, Yves,Cowling, Stephen J.,Goodby, John W.
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p. 5041 - 5049
(2013/06/27)
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- TANNIN INHIBITORS OF HIV
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The invention provides a method to prevent or treat HIV-infection with synthetic tannins, and pharmaceutical compositions comprising synthetic tannins.
- -
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Paragraph 0026
(2013/10/07)
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- Skeletal rearrangement of seven-membered iminosugars: Synthesis of (-)-adenophorine, (-)-1-epi-adenophorine and derivatives and evaluation as glycosidase inhibitors
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The mirror image of natural product (+)-adenophorine along with its 1-epi-, 1-homo-analogs and other derivatives have been synthesized and evaluated as glycosidase inhibitors. The synthetic strategy is based on the skeletal rearrangement of tetrahydroxylated C-alkyl azepanes obtained via a Staudinger/azaWittig/alkylation sequence starting from a sugar-derived azidolactol. Several organometallic species have been investigated for the alkylation step including organomagnesium, organolithium, organozinc, organoaluminum and organocerium reagents. While diallylzinc proved to be the most efficient to introduce an allyl substituent, disappointing results were obtained with the other organometallic species leading either to lower yields or no reaction. Enzymatic assays indicate that (-)-adenophorine is a moderate α-l-fucosidase inhibitor.
- Mondon, Martine,Lecornué, Frédéric,Guillard, Jér?me,Nakagawa, Shinpei,Kato, Atsushi,Blériot, Yves
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p. 4803 - 4812
(2013/08/23)
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- Mannose-binding geometry of pradimicin A
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Pradimicins (PRMs) and benanomicins are the only family of non-peptidic natural products with lectin-like properties, that is, they recognize D-mannopyranoside (Man) in the presence of Ca2+ ions. Coupled with their unique Man binding ability, t
- Nakagawa, Yu,Doi, Takashi,Taketani, Takara,Takegoshi,Igarashi, Yasuhiro,Ito, Yukishige
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p. 10516 - 10525
(2013/08/23)
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- Intramolecular OH×××FC hydrogen bonding in fluorinated carbohydrates: CHF is a better hydrogen bond acceptor than CF2
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An intramolecular bifurcated H-bond from the axial HO-2 group to the axial F-4 atom and to the O5 atom of α-D-hexopyranosides in apolar solvents is evidenced in 1H NMR spectra. The H-accepting properties of the F atom are modulated by the orien
- Giuffredi, Guy T.,Gouverneur, Veronique,Bernet, Bruno
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supporting information
p. 10524 - 10528
(2013/10/21)
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- Fluorosugar chain termination agents as probes of the sequence specificity of a carbohydrate polymerase
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Naturally occurring carbohydrate polymers are ubiquitous. They are assembled by polymerizing glycosyltransferases, which can generate polysaccharide products with repeating sequence patterns. The fidelity of enzymes of this class is unknown. We report a m
- Brown, Christopher D.,Rusek, Max S.,Kiessling, Laura L.
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supporting information; scheme or table
p. 6552 - 6555
(2012/06/15)
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- Intramolecular base-free sonogashira reaction for the synthesis of benzannulated chiral macrocycles embedded in carbohydrate templates
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A base-free, intramolecular Sonogashira reaction-based general approach has been established for the diversity-oriented synthesis (DOS) of fused bi- and tricyclic systems containing benzannulated, 10- to 13-membered chiral macrocycles embedded in carbohydrate templates. Macrocycles with different ring sizes have been prepared by pre-designing the chiral building blocks. Base-sensitive groups like acetyl and TBDPS survived the reaction conditions. Copyright
- Hussain, Altaf,Yousuf, Syed Khalid,Kumar, Deepak,Lambu, Malikharjunarao,Singh, Baldev,Maity, Sudip,Mukherjee, Debaraj
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supporting information; experimental part
p. 1933 - 1940
(2012/09/22)
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- α-Selective organocatalytic synthesis of 2-deoxygalactosides
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Alpha rules: A thiourea acts as an efficient organocatalyst for the glycosylation of protected galactals to form oligosaccharides containing a 2-deoxymonosaccharide moiety (see scheme). The reaction is highly stereoselective for α-linkages and proceeds by way of a syn-addition mechanism. Copyright
- Balmond, Edward I.,Coe, Diane M.,Galan, M. Carmen,McGarrigle, Eoghan M.
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supporting information
p. 9152 - 9155
(2012/10/29)
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- Fluorine-directed β-galactosylation: Chemical glycosylation development by molecular editing
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Validation of the 2-fluoro substituent as an inert steering group to control chemical glycosylation is presented. A molecular editing study has revealed that the exceptional levels of diastereocontrol in glycosylation processes by using 2-fluoro-3,4,6-tri-O-benzyl glucopyranosyl trichloroacetimidate (TCA) scaffolds are a consequence of the 2R,3S,4S stereotriad. This study has also revealed that epimerization at C4, results in a substantial enhancement in β-selectivity (up to β/α 300:1). Copyright
- Durantie, Estelle,Bucher, Christoph,Gilmour, Ryan
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p. 8208 - 8215
(2012/08/27)
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- 2,4,6-Trichloro-1,3,5-triazine (TCT) mediated one-pot sequential functionalisation of glycosides for the generation of orthogonally protected monosaccharide building blocks
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Orthogonally protected monosaccharide building blocks have been prepared using TCT in a one-pot multicomponent transformation. The process involves successive steps of arylidene acetalation, esterification and regioselective reductive acetal cleavage. High regioselectivity, scope for using a broad range of substrates, functional group tolerance, mild reaction conditions, easy handling process and wide application range are a few advantages of the current process.
- Tatina, Madhubabu,Yousuf, Syed Khalid,Mukherjee, Debaraj
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supporting information; experimental part
p. 5357 - 5360
(2012/07/30)
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- Defining oxyanion reactivities in base-promoted glycosylations
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Saccharide oxyanions obtained by base treatment could be employed in glycosylation to give oligosaccharides with high stereo- and regioselectivities.
- Matwiejuk, Martin,Thiem, Joachim
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supporting information; experimental part
p. 8379 - 8381
(2011/09/14)
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- New method for regioselective glycosylation employing saccharide oxyanions
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As an alternative concept for glycosylation, the prior activation of acceptor hydroxy groups for selective glycosidic bond formation, was investigated to give complex oligosaccharides. Oxyanions obtained from partially protected saccharides were glycosylated by employing glycopyranosyl halides, and the regiochemical results were studied. Initially, partially methylated methyl-α-D-glucopyranosides were used as a model system to study the underlying mechanistic principles of base-promoted glycosylation. High regioselectivities and stereospecific glycosidic bond formations were achieved, and the scope of the methodology was extended with different perbenzylated glycosyl donors.
- Matwiejuk, Martin,Thiem, Joachim
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scheme or table
p. 5860 - 5878
(2011/11/06)
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- The UDP-Galp mutase catalyzed isomerization: Synthesis and evaluation of 1,4-anhydro-β-d-galactopyranose and its [2.2.2] methylene homologue
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The synthesis of 1,4-anhydro-β-d-galactopyranose (1,5-anhydro-α- d-galactofuranose), a proposed intermediate in the ring contraction isomerisation catalyzed by UDP-galactopyranose mutase, together with its [2.2.2] bicyclic methylene homologue, synthesised as a possible competitive inhibitor or alternative substrate, are reported. Neither compound was found to be an inhibitor or substrate for UDP-galactopyranose mutase from Klebsiella pneumoniae.
- Sadeghi-Khomami, Ali,Forcada, Tatiana J.,Wilson, Claire,Sanders, David A. R.,Thomas, Neil R.
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supporting information; experimental part
p. 1596 - 1602
(2010/07/04)
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- Convergent synthesis of the tetrasaccharide repeating unit related to the O-antigenic polysaccharide of Escherichia coli 78
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A convergent synthesis of the tetrasaccharide repeating unit of the O-antigenic cell wall polysaccharide of Escherichia coli 78, as the corresponding methyl glycoside (I), is being reported. It involved stereoselective glycosidation of a β-linked mannodis
- Maity, Sajal K.,Patra, Amarendra,Ghosh, Rina
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experimental part
p. 2809 - 2814
(2010/06/16)
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- Low-concentration 12-trans β-selective glycosylation strategy and its applications in oligosaccharide synthesis
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This study develops an operationally easy, efficient, and general 1,2-trans β-selective glycosylation reaction that proceeds in the absence of a C2 acyl function. This process employs chemically stable thioglycosyl donors and low substrate concentrations to achieve excellent β-selectivities in glycosylation reactions. This method is widely applicable to a range of glycosyl substrates irrespective of their structures and hydroxyl-protecting functions. This low-concentration 1,2-trans β-selective glycosylation in carbohydrate chemistry removes the restriction of using highly reactive thioglycosides to construct 1,2-trans β-glycosidic bonds. This is beneficial to the design of new strategies for oligosaccharide synthesis, as illustrated in the preparation of the biologically relevant β-(1-6)-glucan trisaccharide, β-linked Gb3 and isoGb3 derivatives.
- Chao, Chin-Sheng,Li, Chen-Wei,Chen, Min-Chun,Chang, Shih-Sheng,Mong, Kwok-Kong Tony
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supporting information; experimental part
p. 10972 - 10982
(2010/04/30)
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- A unique approach to the synthesis of a dengue vaccine and the novel tetrasaccharide that results
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An approach to the development of a dengue vaccine by synthesizing the hexasaccharide epitope on the viral surface is examined. The stereochemical and structural challenges include the synthesis of a β-mannoside bond. Synthesis of this bond is approached
- Jalsa, Nigel Kevin,Singh, Gurdial
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scheme or table
p. 867 - 874
(2009/09/30)
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- Synthesis of S-linked carbohydrate analogues via a Ferrier reaction
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In this work, the synthetic utility of the Ferrier reaction to access S-linked disaccharides and S-linked glycoamino acids has been probed. Significantly, entry to a range of 1,4- and 1,6-S-linked disaccharides has been achieved using glycals derived from glucose and galactose, and sulfur containing coupling partners derived from methyl α-d-glucopyranoside. Access to S-linked glycoamino acids and glycopeptides has also been achieved using protected cysteine and homocysteine coupling partners within the Ferrier reaction. Functionalisation of the Ferrier products, for example, via dihydroxylation using OsO4 or amino acid coupling, and deprotection of the targets have also been achieved. In this way, entry to materials of interest as mimics of biologically interesting disaccharides and glycopeptides has been realised, including targets derived from rare sugars such as talopyranose and gulopyranose.
- Ellis, David,Norman, Sarah E.,Osborn, Helen M.I.
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p. 2832 - 2854
(2008/09/19)
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- Synthesis of a pentasaccharide repeating unit of the extracellular polysaccharide produced by Lactobacillus delbrueckii subsp. bulgaricus 291
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A pentasaccharide methyl glycoside has been synthesized efficiently using a modified glycosylation strategy. This pentasaccharide is a repeating unit of the exopolysaccharides produced by Lactobacillus delbrueckii subsp. bulgaricus 291.
- Tiwari, Pallavi,Misra, Anup Kumar
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p. 239 - 248
(2008/02/12)
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- Direct and convenient method of regioselective benzylation of methyl α-D-glucopyranoside
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A facile and convenient method for the direct preparation of methyl 2,3,6-tri-O-benzyl-α-D-glucopyranoside (2) by the regioselective benzylation of methyl α-D-glucopyranoside (1) with benzyl bromide in the presence of mild bases K2CO3 and KOH (1:1) withou
- Li, Xiaoliu,Li, Zhiwei,Zhang, Pingzhu,Chen, Hua,Ikegami, Shiro
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p. 2195 - 2202
(2008/02/05)
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- An iodocyclization approach toward diastereoselective synthesis of highly functionalized tetrasubstituted tetrahydrofurans with 2,5-trans and 2,5-cis relationships from pyranoside derived acyclic oximes
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An efficient method to obtain novel tetrasubstituted tetrahydrofurans with C2 and C5 substitution in trans- and cis-relative configurations has been reported.
- Kumar, Vikas,Gauniyal, Harsh Mohan,Shaw, Arun K.
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p. 2069 - 2078
(2008/02/11)
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- Stereoselective mannich-like reactions of ester enolates generated on sugar templates: A novel access to a key intermediate for 1β-methylcarbapenem synthesis
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The Mannich-like reactions of the enolates generated from 2,3-di-O-protected 6-deoxy-4-O-propionyl-α-D-glucopyranosides with (3R,4R)-4-acetoxy-3-((R)-1-(t-butyldimethylsilyloxy)ethyl ]azetidin-2-one were investigated. The corresponding 2,3-di-O-methyl derivative provided the Mannich adduct in good to excellent stereoselectivity. From the major adduct, the azetidin-2-one incorporating an α-methyl acetic acid side chain at the C-4 position with ?-configuration was obtained by alkaline hydrolysis. This product, (3S,4S)-3-[(R)-1-(t-butyldimethylsilyloxy)ethyl 1-4-1(R)-1-carboxyethylJazetidin-2-one, is a useful intermediate for the 1 ?-methylcarbapenem synthesis.
- Sasaki, Daisuke,Sawamoto, Daisuke,Takao, Ken-ichi,Tadano, Kin-ichi,Okue, Masayuki,Ajito, Keiichi
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p. 103 - 110
(2008/02/13)
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- 4,6-O-benzylidene directed β-mannosylation without intermediate triflate formation? Comparison of trichloroacetimidate and disal donors in microwave-promoted glycosylations under neutral conditions
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4,6-Benzylidene-protected mannosyl donors have emerged as efficient tools for the formation of 1,2-cis β-mannosides, which otherwise are difficult to access. Previously studied sulfoxide and trichloroacetimidate mannosyl donors were activated with strong
- Worm-Leonhard, Kasper,Larsen, Kim,Jensen, Knud J.
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p. 349 - 368
(2008/04/12)
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- PdCl2/CuCl2-catalysed chlorocyclisation of sugar-derived aminoalkenitols in the synthesis of new iminohexitols
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The total synthesis of two novel l-ido and l-altro configured 6-chloro-1,5,6-trideoxyiminohexitols featuring a highly diastereoselective Pd(II)/CuCl2-catalysed chlorocyclisation of sugar-derived aminoalkenitols has been accomplished. The requis
- Szolcsányi, Peter,Gracza, Tibor
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p. 8498 - 8502
(2007/10/03)
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- Bicyclic carbohydrate-derived scaffolds for combinatorial libraries
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A bicyclic scaffold derived from the natural monosaccharide d-glucose, and possessing several diversity sites, was linked to various resins through the primary (C-6) hydroxyl and decorated on the solid phase: the hydroxyl group at C-4 was functionalized a
- Cervi, Giovanni,Peri, Francesco,Battistini, Carlo,Gennari, Cesare,Nicotra, Francesco
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p. 3349 - 3367
(2007/10/03)
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